Remove unused unimplemented::cause enum values and document remaining ones

Co-authored-by: tgrabiec <283695+tgrabiec@users.noreply.github.com>

.github/copilot-instructions.md

@@ -0,0 +1,86 @@
+# ScyllaDB Development Instructions
+
+## Project Context
+High-performance distributed NoSQL database. Core values: performance, correctness, readability.
+
+## Build System
+
+### Modern Build (configure.py + ninja)
+```bash
+# Configure (run once per mode, or when switching modes)
+./configure.py --mode=<mode>  # mode: dev, debug, release, sanitize
+
+# Build everything
+ninja <mode>-build  # e.g., ninja dev-build
+
+# Build Scylla binary only (sufficient for Python integration tests)
+ninja build/<mode>/scylla
+
+# Build specific test
+ninja build/<mode>/test/boost/<test_name>
+```
+
+## Running Tests
+
+### C++ Unit Tests
+```bash
+# Run all tests in a file
+./test.py --mode=<mode> test/<suite>/<test_name>.cc
+
+# Run a single test case from a file
+./test.py --mode=<mode> test/<suite>/<test_name>.cc::<test_case_name>
+
+# Examples
+./test.py --mode=dev test/boost/memtable_test.cc
+./test.py --mode=dev test/raft/raft_server_test.cc::test_check_abort_on_client_api
+```
+
+**Important:** 
+- Use full path with `.cc` extension (e.g., `test/boost/test_name.cc`, not `boost/test_name`)
+- To run a single test case, append `::<test_case_name>` to the file path
+- If you encounter permission issues with cgroup metric gathering, add `--no-gather-metrics` flag
+
+**Rebuilding Tests:**
+- test.py does NOT automatically rebuild when test source files are modified
+- Many tests are part of composite binaries (e.g., `combined_tests` in test/boost contains multiple test files)
+- To find which binary contains a test, check `configure.py` in the repository root (primary source) or `test/<suite>/CMakeLists.txt`
+- To rebuild a specific test binary: `ninja build/<mode>/test/<suite>/<binary_name>`
+- Examples: 
+  - `ninja build/dev/test/boost/combined_tests` (contains group0_voter_calculator_test.cc and others)
+  - `ninja build/dev/test/raft/replication_test` (standalone Raft test)
+
+### Python Integration Tests
+```bash
+# Only requires Scylla binary (full build usually not needed)
+ninja build/<mode>/scylla
+
+# Run all tests in a file
+./test.py --mode=<mode> <test_path>
+
+# Run a single test case from a file
+./test.py --mode=<mode> <test_path>::<test_function_name>
+
+# Examples
+./test.py --mode=dev alternator/
+./test.py --mode=dev cluster/test_raft_voters::test_raft_limited_voters_retain_coordinator
+
+# Optional flags
+./test.py --mode=dev cluster/test_raft_no_quorum -v  # Verbose output
+./test.py --mode=dev cluster/test_raft_no_quorum --repeat 5  # Repeat test 5 times
+```
+
+**Important:**
+- Use path without `.py` extension (e.g., `cluster/test_raft_no_quorum`, not `cluster/test_raft_no_quorum.py`)
+- To run a single test case, append `::<test_function_name>` to the file path
+- Add `-v` for verbose output
+- Add `--repeat <num>` to repeat a test multiple times
+- After modifying C++ source files, only rebuild the Scylla binary for Python tests - building the entire repository is unnecessary
+
+## Code Philosophy
+- Performance matters in hot paths (data read/write, inner loops)
+- Self-documenting code through clear naming
+- Comments explain "why", not "what"
+- Prefer standard library over custom implementations
+- Strive for simplicity and clarity, add complexity only when clearly justified
+- Question requests: don't blindly implement requests - evaluate trade-offs, identify issues, and suggest better alternatives when appropriate
+- Consider different approaches, weigh pros and cons, and recommend the best fit for the specific context

.github/instructions/cpp.instructions.md

@@ -0,0 +1,115 @@
+---
+applyTo: "**/*.{cc,hh}"
+---
+
+# C++ Guidelines
+
+**Important:** Always match the style and conventions of existing code in the file and directory.
+
+## Memory Management
+- Prefer stack allocation whenever possible
+- Use `std::unique_ptr` by default for dynamic allocations
+- `new`/`delete` are forbidden (use RAII)
+- Use `seastar::lw_shared_ptr` or `seastar::shared_ptr` for shared ownership within same shard
+- Use `seastar::foreign_ptr` for cross-shard sharing
+- Avoid `std::shared_ptr` except when interfacing with external C++ APIs
+- Avoid raw pointers except for non-owning references or C API interop
+
+## Seastar Asynchronous Programming
+- Use `seastar::future<T>` for all async operations
+- Prefer coroutines (`co_await`, `co_return`) over `.then()` chains for readability
+- Coroutines are preferred over `seastar::do_with()` for managing temporary state
+- In hot paths where futures are ready, continuations may be more efficient than coroutines
+- Chain futures with `.then()`, don't block with `.get()` (unless in `seastar::thread` context)
+- All I/O must be asynchronous (no blocking calls)
+- Use `seastar::gate` for shutdown coordination
+- Use `seastar::semaphore` for resource limiting (not `std::mutex`)
+- Break long loops with `maybe_yield()` to avoid reactor stalls
+
+## Coroutines
+```cpp
+seastar::future<T> func() {
+    auto result = co_await async_operation();
+    co_return result;
+}
+```
+
+## Error Handling
+- Throw exceptions for errors (futures propagate them automatically)
+- In data path: avoid exceptions, use `std::expected` (or `boost::outcome`) instead
+- Use standard exceptions (`std::runtime_error`, `std::invalid_argument`)
+- Database-specific: throw appropriate schema/query exceptions
+
+## Performance
+- Pass large objects by `const&` or `&&` (move semantics)
+- Use `std::string_view` for non-owning string references
+- Avoid copies: prefer move semantics
+- Use `utils::chunked_vector` instead of `std::vector` for large allocations (>128KB)
+- Minimize dynamic allocations in hot paths
+
+## Database-Specific Types
+- Use `schema_ptr` for schema references
+- Use `mutation` and `mutation_partition` for data modifications
+- Use `partition_key` and `clustering_key` for keys
+- Use `api::timestamp_type` for database timestamps
+- Use `gc_clock` for garbage collection timing
+
+## Style
+- C++23 standard (prefer modern features, especially coroutines)
+- Use `auto` when type is obvious from RHS
+- Avoid `auto` when it obscures the type
+- Use range-based for loops: `for (const auto& item : container)`
+- Use standard algorithms when they clearly simplify code (e.g., replacing 10-line loops)
+- Avoid chaining multiple algorithms if a straightforward loop is clearer
+- Mark functions and variables `const` whenever possible
+- Use scoped enums: `enum class` (not unscoped `enum`)
+
+## Headers
+- Use `#pragma once`
+- Include order: own header, C++ std, Seastar, Boost, project headers
+- Forward declare when possible
+- Never `using namespace` in headers (exception: `using namespace seastar` is globally available via `seastarx.hh`)
+
+## Documentation
+- Public APIs require clear documentation
+- Implementation details should be self-evident from code
+- Use `///` or Doxygen `/** */` for public documentation, `//` for implementation notes - follow the existing style
+
+## Naming
+- `snake_case` for most identifiers (classes, functions, variables, namespaces)
+- Template parameters: `CamelCase` (e.g., `template<typename ValueType>`)
+- Member variables: prefix with `_` (e.g., `int _count;`)
+- Structs (value-only): no `_` prefix on members
+- Constants and `constexpr`: `snake_case` (e.g., `static constexpr int max_size = 100;`)
+- Files: `.hh` for headers, `.cc` for source
+
+## Formatting
+- 4 spaces indentation, never tabs
+- Opening braces on same line as control structure (except namespaces)
+- Space after keywords: `if (`, `while (`, `return `
+- Whitespace around operators matches precedence: `*a + *b` not `* a+* b`
+- Line length: keep reasonable (<160 chars), use continuation lines with double indent if needed
+- Brace all nested scopes, even single statements
+- Minimal patches: only format code you modify, never reformat entire files
+
+## Logging
+- Use structured logging with appropriate levels: DEBUG, INFO, WARN, ERROR
+- Include context in log messages (e.g., request IDs)
+- Never log sensitive data (credentials, PII)
+
+## Forbidden
+- `malloc`/`free`
+- `printf` family (use logging or fmt)
+- Raw pointers for ownership
+- `using namespace` in headers
+- Blocking operations: `std::sleep`, `std::read`, `std::mutex` (use Seastar equivalents)
+- `std::atomic` (reserved for very special circumstances only)
+- Macros (use `inline`, `constexpr`, or templates instead)
+
+## Testing
+When modifying existing code, follow TDD: create/update test first, then implement.
+- Examine existing tests for style and structure
+- Use Boost.Test framework
+- Use `SEASTAR_THREAD_TEST_CASE` for Seastar asynchronous tests
+- Aim for high code coverage, especially for new features and bug fixes
+- Maintain bisectability: all tests must pass in every commit. Mark failing tests with `BOOST_FAIL()` or similar, then fix in subsequent commit

.github/instructions/python.instructions.md

@@ -0,0 +1,51 @@
+---
+applyTo: "**/*.py"
+---
+
+# Python Guidelines
+
+**Important:** Match existing code style. Some directories (like `test/cqlpy` and `test/alternator`) prefer simplicity over type hints and docstrings.
+
+## Style
+- Follow PEP 8
+- Use type hints for function signatures (unless directory style omits them)
+- Use f-strings for formatting
+- Line length: 160 characters max
+- 4 spaces for indentation
+
+## Imports
+Order: standard library, third-party, local imports
+```python
+import os
+import sys
+
+import pytest
+from cassandra.cluster import Cluster
+
+from test.utils import setup_keyspace
+```
+
+Never use `from module import *`
+
+## Documentation
+All public functions/classes need docstrings (unless the current directory conventions omit them):
+```python
+def my_function(arg1: str, arg2: int) -> bool:
+    """
+    Brief summary of function purpose.
+
+    Args:
+        arg1: Description of first argument.
+        arg2: Description of second argument.
+
+    Returns:
+        Description of return value.
+    """
+    pass
+```
+
+## Testing Best Practices
+- Maintain bisectability: all tests must pass in every commit
+- Mark currently-failing tests with `@pytest.mark.xfail`, unmark when fixed
+- Use descriptive names that convey intent
+- Docstrings/comments should explain what the test verifies and why, and if it reproduces a specific issue or how it fits into the larger test suite

.github/workflows/docs-validate-metrics.yml

@@ -0,0 +1,34 @@
+name: Docs / Validate metrics
+
+on:
+  pull_request:
+    branches:
+      - master
+      - enterprise
+    paths:
+      - '**/*.cc'
+      - 'scripts/metrics-config.yml' 
+      - 'scripts/get_description.py'
+      - 'docs/_ext/scylladb_metrics.py'
+
+jobs:
+  validate-metrics:
+    runs-on: ubuntu-latest
+    name: Check metrics documentation coverage
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        submodules: true
+      
+    - name: Set up Python
+      uses: actions/setup-python@v6
+      with:
+        python-version: '3.10'
+        
+    - name: Install dependencies
+      run: pip install PyYAML
+        
+    - name: Validate metrics
+      run: python3 scripts/get_description.py --validate -c scripts/metrics-config.yml

CMakeLists.txt

@@ -116,6 +116,7 @@ list(APPEND absl_cxx_flags
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     list(APPEND ABSL_GCC_FLAGS ${absl_cxx_flags})
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    list(APPEND absl_cxx_flags "-Wno-deprecated-builtins")
     list(APPEND ABSL_LLVM_FLAGS ${absl_cxx_flags})
 endif()
 set(ABSL_DEFAULT_LINKOPTS
@@ -163,7 +164,45 @@ file(MAKE_DIRECTORY "${scylla_gen_build_dir}")
 include(add_version_library)
 generate_scylla_version()
 
+option(Scylla_USE_PRECOMPILED_HEADER "Use precompiled header for Scylla" ON)
+add_library(scylla-precompiled-header STATIC exported_templates.cc)
+target_link_libraries(scylla-precompiled-header PRIVATE
+    absl::headers
+    absl::btree
+    absl::hash
+    absl::raw_hash_set
+    Seastar::seastar
+    Snappy::snappy
+    systemd
+    ZLIB::ZLIB
+    lz4::lz4_static
+    zstd::zstd_static)
+if (Scylla_USE_PRECOMPILED_HEADER)
+  set(Scylla_USE_PRECOMPILED_HEADER_USE ON)
+  find_program(DISTCC_EXEC NAMES distcc OPTIONAL)
+  if (DISTCC_EXEC)
+    if(DEFINED ENV{DISTCC_HOSTS})
+      set(Scylla_USE_PRECOMPILED_HEADER_USE OFF)
+      message(STATUS "Disabling precompiled header usage because distcc exists and DISTCC_HOSTS is set, assuming you're using distributed compilation.")
+    else()
+      file(REAL_PATH "~/.distcc/hosts" DIST_CC_HOSTS_PATH EXPAND_TILDE)
+      if (EXISTS ${DIST_CC_HOSTS_PATH})
+        set(Scylla_USE_PRECOMPILED_HEADER_USE OFF)
+        message(STATUS "Disabling precompiled header usage because distcc and ~/.distcc/hosts exists, assuming you're using distributed compilation.")
+      endif()
+    endif()
+  endif()
+  if (Scylla_USE_PRECOMPILED_HEADER_USE)
+    message(STATUS "Using precompiled header for Scylla - remember to add `sloppiness = pch_defines,time_macros` to ccache.conf, if you're using ccache.")
+    target_precompile_headers(scylla-precompiled-header PRIVATE "stdafx.hh")
+    target_compile_definitions(scylla-precompiled-header PRIVATE SCYLLA_USE_PRECOMPILED_HEADER)
+  endif()
+else()
+  set(Scylla_USE_PRECOMPILED_HEADER_USE OFF)
+endif()
+
 add_library(scylla-main STATIC)
+
 target_sources(scylla-main
   PRIVATE
     absl-flat_hash_map.cc
@@ -208,6 +247,7 @@ target_link_libraries(scylla-main
     ZLIB::ZLIB
     lz4::lz4_static
     zstd::zstd_static
+    scylla-precompiled-header
 )
 
 option(Scylla_CHECK_HEADERS

UNIMPLEMENTED_ENUM_ANALYSIS.md

@@ -0,0 +1,109 @@
+# Analysis of unimplemented::cause Enum Values
+
+This document provides an analysis of the `unimplemented::cause` enum values after cleanup.
+
+## Removed Unused Enum Values (20 values removed)
+
+The following enum values had **zero usages** in the codebase and have been removed:
+
+- `LWT` - Lightweight transactions
+- `PAGING` - Query result paging
+- `AUTH` - Authentication
+- `PERMISSIONS` - Permission checking
+- `COUNTERS` - Counter columns
+- `MIGRATIONS` - Schema migrations
+- `GOSSIP` - Gossip protocol
+- `TOKEN_RESTRICTION` - Token-based restrictions
+- `LEGACY_COMPOSITE_KEYS` - Legacy composite key handling
+- `COLLECTION_RANGE_TOMBSTONES` - Collection range tombstones
+- `RANGE_DELETES` - Range deletion operations
+- `COMPRESSION` - Compression features
+- `NONATOMIC` - Non-atomic operations
+- `CONSISTENCY` - Consistency level handling
+- `WRAP_AROUND` - Token wrap-around handling
+- `STORAGE_SERVICE` - Storage service operations
+- `SCHEMA_CHANGE` - Schema change operations
+- `MIXED_CF` - Mixed column family operations
+- `SSTABLE_FORMAT_M` - SSTable format M
+
+## Remaining Enum Values (8 values kept)
+
+### 1. `API` (4 usages)
+**Impact**: REST API features that are not fully implemented.
+
+**Usages**:
+- `api/column_family.cc:1052` - Fails when `split_output` parameter is used in major compaction
+- `api/compaction_manager.cc:100,146,216` - Warns when force_user_defined_compaction or related operations are called
+
+**User Impact**: Some REST API endpoints for compaction management are stubs and will warn or fail.
+
+### 2. `INDEXES` (6 usages)
+**Impact**: Secondary index features not fully supported.
+
+**Usages**:
+- `api/column_family.cc:433,440,449,456` - Warns about index-related operations
+- `cql3/restrictions/statement_restrictions.cc:1158` - Fails when attempting filtering on collection columns without proper indexing
+- `cql3/statements/update_statement.cc:149` - Warns about index operations
+
+**User Impact**: Some advanced secondary index features (especially filtering on collections) are not available.
+
+### 3. `TRIGGERS` (2 usages)
+**Impact**: Trigger support is not implemented.
+
+**Usages**:
+- `db/schema_tables.cc:2017` - Warns when loading trigger metadata from schema tables
+- `service/storage_proxy.cc:4166` - Warns when processing trigger-related operations
+
+**User Impact**: Cassandra triggers (stored procedures that execute on data changes) are not supported.
+
+### 4. `METRICS` (1 usage)
+**Impact**: Some query processor metrics are not collected.
+
+**Usages**:
+- `cql3/query_processor.cc:585` - Warns about missing metrics implementation
+
+**User Impact**: Minor - some internal metrics may not be available.
+
+### 5. `VALIDATION` (4 usages)
+**Impact**: Schema validation checks are partially implemented.
+
+**Usages**:
+- `cql3/functions/token_fct.hh:38` - Warns about validation in token functions
+- `cql3/statements/drop_keyspace_statement.cc:40` - Warns when dropping keyspace
+- `cql3/statements/truncate_statement.cc:87` - Warns when truncating table
+- `service/migration_manager.cc:750` - Warns during schema migrations
+
+**User Impact**: Some schema validation checks are skipped (with warnings logged).
+
+### 6. `REVERSED` (1 usage)
+**Impact**: Reversed type support in CQL protocol.
+
+**Usages**:
+- `transport/server.cc:2085` - Fails when trying to use reversed types in CQL protocol
+
+**User Impact**: Reversed types are not supported in the CQL protocol implementation.
+
+### 7. `HINT` (1 usage)
+**Impact**: Hint replaying is not implemented.
+
+**Usages**:
+- `db/batchlog_manager.cc:251` - Warns when attempting to replay hints
+
+**User Impact**: Cassandra hints (temporary storage of writes when nodes are down) are not supported.
+
+### 8. `SUPER` (2 usages)
+**Impact**: Super column families are not supported.
+
+**Usages**:
+- `db/legacy_schema_migrator.cc:157` - Fails when encountering super column family in legacy schema
+- `db/schema_tables.cc:2288` - Fails when encountering super column family in schema tables
+
+**User Impact**: Super column families (legacy Cassandra feature) will cause errors if encountered in legacy data or schema migrations.
+
+## Summary
+
+- **Removed**: 20 unused enum values (76% reduction)
+- **Kept**: 8 actively used enum values (24% remaining)
+- **Total lines removed**: ~40 lines from enum definition and switch statement
+
+The remaining enum values represent actual unimplemented features that users may encounter, with varying impacts ranging from warnings (TRIGGERS, METRICS, VALIDATION, HINT) to failures (API split_output, INDEXES on collections, REVERSED types, SUPER tables).

alternator/CMakeLists.txt

@@ -34,5 +34,8 @@ target_link_libraries(alternator
     idl
     absl::headers)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(alternator REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers alternator
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

alternator/executor.cc

@@ -888,7 +888,7 @@ future<executor::request_return_type> executor::describe_table(client_state& cli
 
     schema_ptr schema = get_table(_proxy, request);
     get_stats_from_schema(_proxy, *schema)->api_operations.describe_table++;
-    tracing::add_table_name(trace_state, schema->ks_name(), schema->cf_name());
+    tracing::add_alternator_table_name(trace_state, schema->cf_name());
 
     rjson::value table_description = co_await fill_table_description(schema, table_status::active, _proxy, client_state, trace_state, permit);
     rjson::value response = rjson::empty_object();
@@ -989,7 +989,7 @@ future<executor::request_return_type> executor::delete_table(client_state& clien
     std::string table_name = get_table_name(request);
 
     std::string keyspace_name = executor::KEYSPACE_NAME_PREFIX + table_name;
-    tracing::add_table_name(trace_state, keyspace_name, table_name);
+    tracing::add_alternator_table_name(trace_state, table_name);
     auto& p = _proxy.container();
 
     schema_ptr schema = get_table(_proxy, request);
@@ -1008,8 +1008,8 @@ future<executor::request_return_type> executor::delete_table(client_state& clien
                 throw api_error::resource_not_found(fmt::format("Requested resource not found: Table: {} not found", table_name));
             }
 
-            auto m = co_await service::prepare_column_family_drop_announcement(_proxy, keyspace_name, table_name, group0_guard.write_timestamp(), service::drop_views::yes);
+            auto m = co_await service::prepare_column_family_drop_announcement(p.local(), keyspace_name, table_name, group0_guard.write_timestamp(), service::drop_views::yes);
-            auto m2 = co_await service::prepare_keyspace_drop_announcement(_proxy, keyspace_name, group0_guard.write_timestamp());
+            auto m2 = co_await service::prepare_keyspace_drop_announcement(p.local(), keyspace_name, group0_guard.write_timestamp());
 
             std::move(m2.begin(), m2.end(), std::back_inserter(m));
 
@@ -1583,7 +1583,7 @@ static future<executor::request_return_type> create_table_on_shard0(service::cli
     std::unordered_set<std::string> unused_attribute_definitions =
         validate_attribute_definitions("", *attribute_definitions);
 
-    tracing::add_table_name(trace_state, keyspace_name, table_name);
+    tracing::add_alternator_table_name(trace_state, table_name);
 
     schema_builder builder(keyspace_name, table_name);
     auto [hash_key, range_key] = parse_key_schema(request, "");
@@ -1865,10 +1865,10 @@ future<executor::request_return_type> executor::create_table(client_state& clien
     _stats.api_operations.create_table++;
     elogger.trace("Creating table {}", request);
 
-    co_return co_await _mm.container().invoke_on(0, [&, tr = tracing::global_trace_state_ptr(trace_state), request = std::move(request), &sp = _proxy.container(), &g = _gossiper.container(), client_state_other_shard = client_state.move_to_other_shard(), enforce_authorization = bool(_enforce_authorization), warn_authorization = bool(_warn_authorization)]
+    co_return co_await _mm.container().invoke_on(0, [&, tr = tracing::global_trace_state_ptr(trace_state), request = std::move(request), &sp = _proxy.container(), &g = _gossiper.container(), &e = this->container(), client_state_other_shard = client_state.move_to_other_shard(), enforce_authorization = bool(_enforce_authorization), warn_authorization = bool(_warn_authorization)]
                                         (service::migration_manager& mm) mutable -> future<executor::request_return_type> {
         const db::tablets_mode_t::mode tablets_mode = _proxy.data_dictionary().get_config().tablets_mode_for_new_keyspaces(); // type cast
-        co_return co_await create_table_on_shard0(client_state_other_shard.get(), tr, std::move(request), sp.local(), mm, g.local(), enforce_authorization, warn_authorization, _stats, std::move(tablets_mode));
+        co_return co_await create_table_on_shard0(client_state_other_shard.get(), tr, std::move(request), sp.local(), mm, g.local(), enforce_authorization, warn_authorization, e.local()._stats, std::move(tablets_mode));
     });
 }
 
@@ -1930,7 +1930,7 @@ future<executor::request_return_type> executor::update_table(client_state& clien
 
             schema_ptr tab = get_table(p.local(), request);
 
-            tracing::add_table_name(gt, tab->ks_name(), tab->cf_name());
+            tracing::add_alternator_table_name(gt, tab->cf_name());
 
             // the ugly but harmless conversion to string_view here is because
             // Seastar's sstring is missing a find(std::string_view) :-()
@@ -2624,14 +2624,14 @@ std::optional<service::cas_shard> rmw_operation::shard_for_execute(bool needs_re
 // Build the return value from the different RMW operations (UpdateItem,
 // PutItem, DeleteItem). All these return nothing by default, but can
 // optionally return Attributes if requested via the ReturnValues option.
-static future<executor::request_return_type> rmw_operation_return(rjson::value&& attributes, const consumed_capacity_counter& consumed_capacity, uint64_t& metric) {
+static executor::request_return_type rmw_operation_return(rjson::value&& attributes, const consumed_capacity_counter& consumed_capacity, uint64_t& metric) {
     rjson::value ret = rjson::empty_object();
     consumed_capacity.add_consumed_capacity_to_response_if_needed(ret);
     metric += consumed_capacity.get_consumed_capacity_units();
     if (!attributes.IsNull()) {
         rjson::add(ret, "Attributes", std::move(attributes));
     }
-    return make_ready_future<executor::request_return_type>(rjson::print(std::move(ret)));
+    return rjson::print(std::move(ret));
 }
 
 static future<std::unique_ptr<rjson::value>> get_previous_item(
@@ -2697,7 +2697,10 @@ future<executor::request_return_type> rmw_operation::execute(service::storage_pr
         stats& global_stats,
         stats& per_table_stats,
         uint64_t& wcu_total) {
-    auto cdc_opts = cdc::per_request_options{};
+    auto cdc_opts = cdc::per_request_options{
+        .alternator = true,
+        .alternator_streams_increased_compatibility = schema()->cdc_options().enabled() && proxy.data_dictionary().get_config().alternator_streams_increased_compatibility(),
+    };
     if (needs_read_before_write) {
         if (_write_isolation == write_isolation::FORBID_RMW) {
             throw api_error::validation("Read-modify-write operations are disabled by 'forbid_rmw' write isolation policy. Refer to https://github.com/scylladb/scylla/blob/master/docs/alternator/alternator.md#write-isolation-policies for more information.");
@@ -2742,7 +2745,7 @@ future<executor::request_return_type> rmw_operation::execute(service::storage_pr
         if (!is_applied) {
             return make_ready_future<executor::request_return_type>(api_error::conditional_check_failed("The conditional request failed", std::move(_return_attributes)));
         }
-        return rmw_operation_return(std::move(_return_attributes), _consumed_capacity, wcu_total);
+        return make_ready_future<executor::request_return_type>(rmw_operation_return(std::move(_return_attributes), _consumed_capacity, wcu_total));
     });
 }
 
@@ -2856,7 +2859,7 @@ future<executor::request_return_type> executor::put_item(client_state& client_st
     elogger.trace("put_item {}", request);
 
     auto op = make_shared<put_item_operation>(*_parsed_expression_cache, _proxy, std::move(request));
-    tracing::add_table_name(trace_state, op->schema()->ks_name(), op->schema()->cf_name());
+    tracing::add_alternator_table_name(trace_state, op->schema()->cf_name());
     const bool needs_read_before_write = op->needs_read_before_write();
 
     co_await verify_permission(_enforce_authorization, _warn_authorization, client_state, op->schema(), auth::permission::MODIFY, _stats);
@@ -2960,7 +2963,7 @@ future<executor::request_return_type> executor::delete_item(client_state& client
 
     auto op = make_shared<delete_item_operation>(*_parsed_expression_cache, _proxy, std::move(request));
     lw_shared_ptr<stats> per_table_stats = get_stats_from_schema(_proxy, *(op->schema()));
-    tracing::add_table_name(trace_state, op->schema()->ks_name(), op->schema()->cf_name());
+    tracing::add_alternator_table_name(trace_state, op->schema()->cf_name());
     const bool needs_read_before_write = _proxy.data_dictionary().get_config().alternator_force_read_before_write() || op->needs_read_before_write();
 
     co_await verify_permission(_enforce_authorization, _warn_authorization, client_state, op->schema(), auth::permission::MODIFY, _stats);
@@ -3054,6 +3057,9 @@ static future<> cas_write(service::storage_proxy& proxy, schema_ptr schema, serv
     auto timeout = executor::default_timeout();
     auto op = seastar::make_shared<put_or_delete_item_cas_request>(schema, std::move(mutation_builders));
     auto cdc_opts = cdc::per_request_options{
+        .alternator = true,
+        .alternator_streams_increased_compatibility =
+                schema->cdc_options().enabled() && proxy.data_dictionary().get_config().alternator_streams_increased_compatibility(),
     };
     return proxy.cas(schema, std::move(cas_shard), op, nullptr, to_partition_ranges(dk),
             {timeout, std::move(permit), client_state, trace_state},
@@ -3104,8 +3110,10 @@ static future<> do_batch_write(service::storage_proxy& proxy,
         utils::chunked_vector<mutation> mutations;
         mutations.reserve(mutation_builders.size());
         api::timestamp_type now = api::new_timestamp();
+        bool any_cdc_enabled = false;
         for (auto& b : mutation_builders) {
             mutations.push_back(b.second.build(b.first, now));
+            any_cdc_enabled |= b.first->cdc_options().enabled();
         }
         return proxy.mutate(std::move(mutations),
                 db::consistency_level::LOCAL_QUORUM,
@@ -3114,7 +3122,10 @@ static future<> do_batch_write(service::storage_proxy& proxy,
                 std::move(permit),
                 db::allow_per_partition_rate_limit::yes,
                 false,
-                cdc::per_request_options{});
+                cdc::per_request_options{
+                    .alternator = true,
+                    .alternator_streams_increased_compatibility = any_cdc_enabled && proxy.data_dictionary().get_config().alternator_streams_increased_compatibility(),
+                });
     } else {
         // Do the write via LWT:
         // Multiple mutations may be destined for the same partition, adding
@@ -3204,7 +3215,7 @@ future<executor::request_return_type> executor::batch_write_item(client_state& c
         per_table_stats->api_operations.batch_write_item++;
         per_table_stats->api_operations.batch_write_item_batch_total += it->value.Size();
         per_table_stats->api_operations.batch_write_item_histogram.add(it->value.Size());
-        tracing::add_table_name(trace_state, schema->ks_name(), schema->cf_name());
+        tracing::add_alternator_table_name(trace_state, schema->cf_name());
 
         std::unordered_set<primary_key, primary_key_hash, primary_key_equal> used_keys(
                 1, primary_key_hash{schema}, primary_key_equal{schema});
@@ -4464,7 +4475,7 @@ future<executor::request_return_type> executor::update_item(client_state& client
     elogger.trace("update_item {}", request);
 
     auto op = make_shared<update_item_operation>(*_parsed_expression_cache, _proxy, std::move(request));
-    tracing::add_table_name(trace_state, op->schema()->ks_name(), op->schema()->cf_name());
+    tracing::add_alternator_table_name(trace_state, op->schema()->cf_name());
     const bool needs_read_before_write = _proxy.data_dictionary().get_config().alternator_force_read_before_write() || op->needs_read_before_write();
 
     co_await verify_permission(_enforce_authorization, _warn_authorization, client_state, op->schema(), auth::permission::MODIFY, _stats);
@@ -4545,7 +4556,7 @@ future<executor::request_return_type> executor::get_item(client_state& client_st
     schema_ptr schema = get_table(_proxy, request);
     lw_shared_ptr<stats> per_table_stats = get_stats_from_schema(_proxy, *schema);
     per_table_stats->api_operations.get_item++;
-    tracing::add_table_name(trace_state, schema->ks_name(), schema->cf_name());
+    tracing::add_alternator_table_name(trace_state, schema->cf_name());
 
     rjson::value& query_key = request["Key"];
     db::consistency_level cl = get_read_consistency(request);
@@ -4694,7 +4705,7 @@ future<executor::request_return_type> executor::batch_get_item(client_state& cli
     uint batch_size = 0;
     for (auto it = request_items.MemberBegin(); it != request_items.MemberEnd(); ++it) {
         table_requests rs(get_table_from_batch_request(_proxy, it));
-        tracing::add_table_name(trace_state, sstring(executor::KEYSPACE_NAME_PREFIX) + rs.schema->cf_name(), rs.schema->cf_name());
+        tracing::add_alternator_table_name(trace_state, rs.schema->cf_name());
         rs.cl = get_read_consistency(it->value);
         std::unordered_set<std::string> used_attribute_names;
         rs.attrs_to_get = ::make_shared<const std::optional<attrs_to_get>>(calculate_attrs_to_get(it->value, *_parsed_expression_cache, used_attribute_names));
@@ -5130,13 +5141,15 @@ static rjson::value encode_paging_state(const schema& schema, const service::pag
     }
     auto pos = paging_state.get_position_in_partition();
     if (pos.has_key()) {
-        auto exploded_ck = pos.key().explode();
+        // Alternator itself allows at most one column in clustering key, but 
-        auto exploded_ck_it = exploded_ck.begin();
+        // user can use Alternator api to access system tables which might have
-        for (const column_definition& cdef : schema.clustering_key_columns()) {
+        // multiple clustering key columns. So we need to handle that case here.
-            rjson::add_with_string_name(last_evaluated_key, std::string_view(cdef.name_as_text()), rjson::empty_object());
+        auto cdef_it = schema.clustering_key_columns().begin();        
-            rjson::value& key_entry = last_evaluated_key[cdef.name_as_text()];
+        for(const auto &exploded_ck : pos.key().explode()) {
-            rjson::add_with_string_name(key_entry, type_to_string(cdef.type), json_key_column_value(*exploded_ck_it, cdef));
+            rjson::add_with_string_name(last_evaluated_key, std::string_view(cdef_it->name_as_text()), rjson::empty_object());
-            ++exploded_ck_it;
+            rjson::value& key_entry = last_evaluated_key[cdef_it->name_as_text()];
+            rjson::add_with_string_name(key_entry, type_to_string(cdef_it->type), json_key_column_value(exploded_ck, *cdef_it));
+            ++cdef_it;
         }
     }
     // To avoid possible conflicts (and thus having to reserve these names) we
@@ -5296,6 +5309,7 @@ future<executor::request_return_type> executor::scan(client_state& client_state,
     elogger.trace("Scanning {}", request);
 
     auto [schema, table_type] = get_table_or_view(_proxy, request);
+    tracing::add_alternator_table_name(trace_state, schema->cf_name());
     get_stats_from_schema(_proxy, *schema)->api_operations.scan++;
     auto segment = get_int_attribute(request, "Segment");
     auto total_segments = get_int_attribute(request, "TotalSegments");
@@ -5775,7 +5789,7 @@ future<executor::request_return_type> executor::query(client_state& client_state
 
     auto [schema, table_type] = get_table_or_view(_proxy, request);
     get_stats_from_schema(_proxy, *schema)->api_operations.query++;
-    tracing::add_table_name(trace_state, schema->ks_name(), schema->cf_name());
+    tracing::add_alternator_table_name(trace_state, schema->cf_name());
 
     rjson::value* exclusive_start_key = rjson::find(request, "ExclusiveStartKey");
     db::consistency_level cl = get_read_consistency(request);

alternator/serialization.cc

@@ -282,15 +282,23 @@ std::string type_to_string(data_type type) {
     return it->second;
 }
 
-bytes get_key_column_value(const rjson::value& item, const column_definition& column) {
+std::optional<bytes> try_get_key_column_value(const rjson::value& item, const column_definition& column) {
     std::string column_name = column.name_as_text();
     const rjson::value* key_typed_value = rjson::find(item, column_name);
     if (!key_typed_value) {
-        throw api_error::validation(fmt::format("Key column {} not found", column_name));
+        return std::nullopt;
     }
     return get_key_from_typed_value(*key_typed_value, column);
 }
 
+bytes get_key_column_value(const rjson::value& item, const column_definition& column) {
+    auto value = try_get_key_column_value(item, column);
+    if (!value) {
+        throw api_error::validation(fmt::format("Key column {} not found", column.name_as_text()));
+    }
+    return std::move(*value);
+}
+
 // Parses the JSON encoding for a key value, which is a map with a single
 // entry whose key is the type and the value is the encoded value.
 // If this type does not match the desired "type_str", an api_error::validation
@@ -380,20 +388,38 @@ clustering_key ck_from_json(const rjson::value& item, schema_ptr schema) {
         return clustering_key::make_empty();
     }
     std::vector<bytes> raw_ck;
-    // FIXME: this is a loop, but we really allow only one clustering key column.
+    // Note: it's possible to get more than one clustering column here, as
+    // Alternator can be used to read scylla internal tables.
     for (const column_definition& cdef : schema->clustering_key_columns()) {
-        bytes raw_value = get_key_column_value(item,  cdef);
+        auto raw_value = get_key_column_value(item,  cdef);
         raw_ck.push_back(std::move(raw_value));
     }
 
     return clustering_key::from_exploded(raw_ck);
 }
 
-position_in_partition pos_from_json(const rjson::value& item, schema_ptr schema) {
+clustering_key_prefix ck_prefix_from_json(const rjson::value& item, schema_ptr schema) {
-    auto ck = ck_from_json(item, schema);
+    if (schema->clustering_key_size() == 0) {
-    if (is_alternator_keyspace(schema->ks_name())) {
+        return clustering_key_prefix::make_empty();
-        return position_in_partition::for_key(std::move(ck));
     }
+    std::vector<bytes> raw_ck;
+    for (const column_definition& cdef : schema->clustering_key_columns()) {
+        auto raw_value = try_get_key_column_value(item,  cdef);
+        if (!raw_value) {
+            break;
+        }
+        raw_ck.push_back(std::move(*raw_value));
+    }
+
+    return clustering_key_prefix::from_exploded(raw_ck);
+}
+
+position_in_partition pos_from_json(const rjson::value& item, schema_ptr schema) {
+    const bool is_alternator_ks = is_alternator_keyspace(schema->ks_name());
+    if (is_alternator_ks) {
+        return position_in_partition::for_key(ck_from_json(item, schema));
+    }
+    
     const auto region_item = rjson::find(item, scylla_paging_region);
     const auto weight_item = rjson::find(item, scylla_paging_weight);
     if (bool(region_item) != bool(weight_item)) {
@@ -413,8 +439,9 @@ position_in_partition pos_from_json(const rjson::value& item, schema_ptr schema)
         } else {
             throw std::runtime_error(fmt::format("Invalid value for weight: {}", weight_view));
         }
-        return position_in_partition(region, weight, region == partition_region::clustered ? std::optional(std::move(ck)) : std::nullopt);
+        return position_in_partition(region, weight, region == partition_region::clustered ? std::optional(ck_prefix_from_json(item, schema)) : std::nullopt);
     }
+    auto ck = ck_from_json(item, schema);
     if (ck.is_empty()) {
         return position_in_partition::for_partition_start();
     }

alternator/server.cc

@@ -13,6 +13,7 @@
 #include <seastar/http/function_handlers.hh>
 #include <seastar/http/short_streams.hh>
 #include <seastar/core/coroutine.hh>
+#include <seastar/coroutine/maybe_yield.hh>
 #include <seastar/util/defer.hh>
 #include <seastar/util/short_streams.hh>
 #include "seastarx.hh"
@@ -32,6 +33,7 @@
 #include "utils/aws_sigv4.hh"
 #include "client_data.hh"
 #include "utils/updateable_value.hh"
+#include <zlib.h>
 
 static logging::logger slogger("alternator-server");
 
@@ -551,6 +553,106 @@ read_entire_stream(input_stream<char>& inp, size_t length_limit) {
     co_return ret;
 }
 
+// safe_gzip_stream is an exception-safe wrapper for zlib's z_stream.
+// The "z_stream" struct is used by zlib to hold state while decompressing a
+// stream of data. It allocates memory which must be freed with inflateEnd(),
+// which the destructor of this class does.
+class safe_gzip_zstream {
+    z_stream _zs;
+public:
+    safe_gzip_zstream() {
+        memset(&_zs, 0, sizeof(_zs));
+        // The strange 16 + WMAX_BITS tells zlib to expect and decode
+        // a gzip header, not a zlib header.
+        if (inflateInit2(&_zs, 16 + MAX_WBITS) != Z_OK) {
+            // Should only happen if memory allocation fails
+            throw std::bad_alloc();
+        }
+    }
+    ~safe_gzip_zstream() {
+        inflateEnd(&_zs);
+    }
+    z_stream* operator->() {
+        return &_zs;
+    }
+    z_stream* get() {
+        return &_zs;
+    }
+    void reset() {
+        inflateReset(&_zs);
+    }
+};
+
+// ungzip() takes a chunked_content with a gzip-compressed request body,
+// uncompresses it, and returns the uncompressed content as a chunked_content.
+// If the uncompressed content exceeds length_limit, an error is thrown.
+static future<chunked_content>
+ungzip(chunked_content&& compressed_body, size_t length_limit) {
+    chunked_content ret;
+    // output_buf can be any size - when uncompressing input_buf, it doesn't
+    // need to fit in a single output_buf, we'll use multiple output_buf for
+    // a single input_buf if needed.
+    constexpr size_t OUTPUT_BUF_SIZE = 4096;
+    temporary_buffer<char> output_buf;
+    safe_gzip_zstream strm;
+    bool complete_stream = false; // empty input is not a valid gzip
+    size_t total_out_bytes = 0;
+    for (const temporary_buffer<char>& input_buf : compressed_body) {
+        if (input_buf.empty()) {
+            continue;
+        }
+        complete_stream = false;
+        strm->next_in = (Bytef*) input_buf.get();
+        strm->avail_in = (uInt) input_buf.size();
+        do {
+            co_await coroutine::maybe_yield();
+            if (output_buf.empty()) {
+                output_buf = temporary_buffer<char>(OUTPUT_BUF_SIZE);
+            }
+            strm->next_out = (Bytef*) output_buf.get();
+            strm->avail_out = OUTPUT_BUF_SIZE;
+            int e = inflate(strm.get(), Z_NO_FLUSH);
+            size_t out_bytes = OUTPUT_BUF_SIZE - strm->avail_out;
+            if (out_bytes > 0) {
+                // If output_buf is nearly full, we save it as-is in ret. But
+                // if it only has little data, better copy to a small buffer.
+                if (out_bytes > OUTPUT_BUF_SIZE/2) {
+                    ret.push_back(std::move(output_buf).prefix(out_bytes));
+                    // output_buf is now empty. if this loop finds more input,
+                    // we'll allocate a new output buffer.
+                } else {
+                    ret.push_back(temporary_buffer<char>(output_buf.get(), out_bytes));
+                }
+                total_out_bytes += out_bytes;
+                if (total_out_bytes > length_limit) {
+                    throw api_error::payload_too_large(fmt::format("Request content length limit of {} bytes exceeded", length_limit));
+                }
+            }
+            if (e == Z_STREAM_END) {
+                // There may be more input after the first gzip stream - in
+                // either this input_buf or the next one. The additional input
+                // should be a second concatenated gzip. We need to allow that
+                // by resetting the gzip stream and continuing the input loop
+                // until there's no more input.
+                strm.reset();
+                if (strm->avail_in == 0) {
+                    complete_stream = true;
+                    break;
+                }
+            } else if (e != Z_OK && e != Z_BUF_ERROR) {
+                // DynamoDB returns an InternalServerError when given a bad
+                // gzip request body. See test test_broken_gzip_content
+                throw api_error::internal("Error during gzip decompression of request body");
+            }
+        } while (strm->avail_in > 0 || strm->avail_out == 0);
+    }
+    if (!complete_stream) {
+        // The gzip stream was not properly finished with Z_STREAM_END
+        throw api_error::internal("Truncated gzip in request body");
+    }
+    co_return ret;
+}
+
 future<executor::request_return_type> server::handle_api_request(std::unique_ptr<request> req) {
     _executor._stats.total_operations++;
     sstring target = req->get_header("X-Amz-Target");
@@ -588,6 +690,21 @@ future<executor::request_return_type> server::handle_api_request(std::unique_ptr
         units.return_units(mem_estimate - new_mem_estimate);
     }
     auto username = co_await verify_signature(*req, content);
+    // If the request is compressed, uncompress it now, after we checked
+    // the signature (the signature is computed on the compressed content).
+    // We apply the request_content_length_limit again to the uncompressed
+    // content - we don't want to allow a tiny compressed request to
+    // expand to a huge uncompressed request.
+    sstring content_encoding = req->get_header("Content-Encoding");
+    if (content_encoding == "gzip") {
+        content = co_await ungzip(std::move(content), request_content_length_limit);
+    } else if (!content_encoding.empty()) {
+        // DynamoDB returns a 500 error for unsupported Content-Encoding.
+        // I'm not sure if this is the best error code, but let's do it too.
+        // See the test test_garbage_content_encoding confirming this case.
+        co_return api_error::internal("Unsupported Content-Encoding");
+    }
+
     // As long as the system_clients_entry object is alive, this request will
     // be visible in the "system.clients" virtual table. When requested, this
     // entry will be formatted by server::ongoing_request::make_client_data().

api/CMakeLists.txt

@@ -106,5 +106,8 @@ target_link_libraries(api
     wasmtime_bindings
     absl::headers)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(api REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers api
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

api/column_family.cc

@@ -66,6 +66,13 @@ static future<json::json_return_type>  get_cf_stats(sharded<replica::database>&
     }, std::plus<int64_t>());
 }
 
+static future<json::json_return_type>  get_cf_stats(sharded<replica::database>& db,
+        std::function<int64_t(const replica::column_family_stats&)> f) {
+    return map_reduce_cf(db, int64_t(0), [f](const replica::column_family& cf) {
+        return f(cf.get_stats());
+    }, std::plus<int64_t>());
+}
+
 static future<json::json_return_type> for_tables_on_all_shards(sharded<replica::database>& db, std::vector<table_info> tables, std::function<future<>(replica::table&)> set) {
     return do_with(std::move(tables), [&db, set] (const std::vector<table_info>& tables) {
         return db.invoke_on_all([&tables, set] (replica::database& db) {
@@ -1066,10 +1073,14 @@ void set_column_family(http_context& ctx, routes& r, sharded<replica::database>&
     });
 
     ss::get_load.set(r, [&db] (std::unique_ptr<http::request> req) {
-        return get_cf_stats(db, &replica::column_family_stats::live_disk_space_used);
+        return get_cf_stats(db, [](const replica::column_family_stats& stats) {
+            return stats.live_disk_space_used.on_disk;
+        });
     });
     ss::get_metrics_load.set(r, [&db] (std::unique_ptr<http::request> req) {
-        return get_cf_stats(db, &replica::column_family_stats::live_disk_space_used);
+        return get_cf_stats(db, [](const replica::column_family_stats& stats) {
+            return stats.live_disk_space_used.on_disk;
+        });
     });
 
     ss::get_keyspaces.set(r, [&db] (const_req req) {

audit/CMakeLists.txt

@@ -17,4 +17,7 @@ target_link_libraries(scylla_audit
   PRIVATE
     cql3)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(scylla_audit REUSE_FROM scylla-precompiled-header)
+endif()
 add_whole_archive(audit scylla_audit)

auth/CMakeLists.txt

@@ -9,6 +9,7 @@ target_sources(scylla_auth
     allow_all_authorizer.cc
     authenticated_user.cc
     authenticator.cc
+    cache.cc
     certificate_authenticator.cc
     common.cc
     default_authorizer.cc
@@ -44,5 +45,8 @@ target_link_libraries(scylla_auth
 
 add_whole_archive(auth scylla_auth)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(scylla_auth REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers scylla_auth
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

auth/allow_all_authenticator.cc

@@ -23,6 +23,7 @@ static const class_registrator<
         cql3::query_processor&,
         ::service::raft_group0_client&,
         ::service::migration_manager&,
+        cache&,
         utils::alien_worker&> registration("org.apache.cassandra.auth.AllowAllAuthenticator");
 
 }

auth/allow_all_authenticator.hh

@@ -12,6 +12,7 @@
 
 #include "auth/authenticated_user.hh"
 #include "auth/authenticator.hh"
+#include "auth/cache.hh"
 #include "auth/common.hh"
 #include "utils/alien_worker.hh"
 
@@ -29,7 +30,7 @@ extern const std::string_view allow_all_authenticator_name;
 
 class allow_all_authenticator final : public authenticator {
 public:
-    allow_all_authenticator(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, utils::alien_worker&) {
+    allow_all_authenticator(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, cache&, utils::alien_worker&) {
     }
 
     virtual future<> start() override {

auth/cache.cc

@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2017-present ScyllaDB
+ */
+
+/*
+ * SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
+ */
+
+#include "auth/cache.hh"
+#include "auth/common.hh"
+#include "auth/roles-metadata.hh"
+#include "cql3/query_processor.hh"
+#include "cql3/untyped_result_set.hh"
+#include "db/consistency_level_type.hh"
+#include "db/system_keyspace.hh"
+#include "schema/schema.hh"
+#include <iterator>
+#include <seastar/coroutine/maybe_yield.hh>
+#include <seastar/core/format.hh>
+
+namespace auth {
+
+logging::logger logger("auth-cache");
+
+cache::cache(cql3::query_processor& qp) noexcept
+    : _current_version(0)
+    , _qp(qp) {
+}
+
+lw_shared_ptr<const cache::role_record> cache::get(const role_name_t& role) const noexcept {
+    auto it = _roles.find(role);
+    if (it == _roles.end()) {
+        return {};
+    }
+    return it->second;
+}
+
+future<lw_shared_ptr<cache::role_record>> cache::fetch_role(const role_name_t& role) const {
+    auto rec = make_lw_shared<role_record>();
+    rec->version = _current_version;
+
+    auto fetch = [this, &role](const sstring& q) {
+        return _qp.execute_internal(q, db::consistency_level::LOCAL_ONE,
+                internal_distributed_query_state(), {role},
+                cql3::query_processor::cache_internal::yes);
+    };
+    // roles
+    {
+        static const sstring q = format("SELECT * FROM {}.{} WHERE role = ?", db::system_keyspace::NAME, meta::roles_table::name);
+        auto rs = co_await fetch(q);
+        if (!rs->empty()) {
+            auto& r = rs->one();
+            rec->is_superuser = r.get_or<bool>("is_superuser", false);
+            rec->can_login = r.get_or<bool>("can_login", false);
+            rec->salted_hash = r.get_or<sstring>("salted_hash", "");
+            if (r.has("member_of")) {
+                auto mo = r.get_set<sstring>("member_of");
+                rec->member_of.insert(
+                        std::make_move_iterator(mo.begin()),
+                        std::make_move_iterator(mo.end()));
+            }
+        } else {
+            // role got deleted
+            co_return nullptr;
+        }
+    }
+    // members
+    {
+        static const sstring q = format("SELECT role, member FROM {}.{} WHERE role = ?", db::system_keyspace::NAME, ROLE_MEMBERS_CF);
+        auto rs = co_await fetch(q);
+        for (const auto& r : *rs) {
+            rec->members.insert(r.get_as<sstring>("member"));
+            co_await coroutine::maybe_yield();
+        }
+    }
+    // attributes
+    {
+        static const sstring q = format("SELECT role, name, value FROM {}.{} WHERE role = ?", db::system_keyspace::NAME, ROLE_ATTRIBUTES_CF);
+        auto rs = co_await fetch(q);
+        for (const auto& r : *rs) {
+            rec->attributes[r.get_as<sstring>("name")] =
+                    r.get_as<sstring>("value");
+            co_await coroutine::maybe_yield();
+        }
+    }
+    // permissions
+    {
+        static const sstring q = format("SELECT role, resource, permissions FROM {}.{} WHERE role = ?", db::system_keyspace::NAME, PERMISSIONS_CF);
+        auto rs = co_await fetch(q);
+        for (const auto& r : *rs) {
+            auto resource = r.get_as<sstring>("resource");
+            auto perms_strings = r.get_set<sstring>("permissions");
+            std::unordered_set<sstring> perms_set(perms_strings.begin(), perms_strings.end());
+            auto pset = permissions::from_strings(perms_set);
+            rec->permissions[std::move(resource)] = std::move(pset);
+            co_await coroutine::maybe_yield();
+        }
+    }
+    co_return rec;
+}
+
+future<> cache::prune_all() noexcept {
+    for (auto it = _roles.begin(); it != _roles.end(); ) {
+        if (it->second->version != _current_version) {
+            _roles.erase(it++);
+            co_await coroutine::maybe_yield();
+        } else {
+            ++it;
+        }
+    }
+    co_return;
+}
+
+future<> cache::load_all() {
+    if (legacy_mode(_qp)) {
+        co_return;
+    }
+    SCYLLA_ASSERT(this_shard_id() == 0);
+    ++_current_version;
+
+    logger.info("Loading all roles");
+    const uint32_t page_size = 128;
+    auto loader = [this](const cql3::untyped_result_set::row& r) -> future<stop_iteration> {
+        const auto name = r.get_as<sstring>("role");
+        auto role = co_await fetch_role(name);
+        if (role) {
+            _roles[name] = role;
+        }
+        co_return stop_iteration::no;
+    };
+    co_await _qp.query_internal(format("SELECT * FROM {}.{}",
+            db::system_keyspace::NAME, meta::roles_table::name),
+            db::consistency_level::LOCAL_ONE, {}, page_size, loader);
+
+    co_await prune_all();
+    for (const auto& [name, role] : _roles) {
+        co_await distribute_role(name, role);
+    }
+    co_await container().invoke_on_others([this](cache& c) -> future<> {
+        c._current_version = _current_version;
+        co_await c.prune_all();
+    });
+}
+
+future<> cache::load_roles(std::unordered_set<role_name_t> roles) {
+    if (legacy_mode(_qp)) {
+        co_return;
+    }
+    for (const auto& name : roles) {
+        logger.info("Loading role {}", name);
+        auto role = co_await fetch_role(name);
+         if (role) {
+            _roles[name] = role;
+        } else {
+            _roles.erase(name);
+        }
+        co_await distribute_role(name, role);
+    }
+}
+
+future<> cache::distribute_role(const role_name_t& name, lw_shared_ptr<role_record> role) {
+    auto role_ptr = role.get();
+    co_await container().invoke_on_others([&name, role_ptr](cache& c) {
+        if (!role_ptr) {
+            c._roles.erase(name);
+            return;
+        }
+        auto role_copy = make_lw_shared<role_record>(*role_ptr);
+        c._roles[name] = std::move(role_copy);
+    });
+}
+
+bool cache::includes_table(const table_id& id) noexcept {
+    return id == db::system_keyspace::roles()->id()
+            || id == db::system_keyspace::role_members()->id()
+            || id == db::system_keyspace::role_attributes()->id()
+            || id == db::system_keyspace::role_permissions()->id();
+}
+
+} // namespace auth

auth/cache.hh

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2025-present ScyllaDB
+ */
+
+/*
+ * SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
+ */
+
+#pragma once
+
+#include <unordered_set>
+#include <unordered_map>
+
+#include <seastar/core/sstring.hh>
+#include <seastar/core/future.hh>
+#include <seastar/core/sharded.hh>
+#include <seastar/core/shared_ptr.hh>
+
+#include <absl/container/flat_hash_map.h>
+
+#include "auth/permission.hh"
+#include "auth/common.hh"
+
+namespace cql3 { class query_processor; }
+
+namespace auth {
+
+class cache : public peering_sharded_service<cache> {
+public:
+    using role_name_t = sstring;
+    using version_tag_t = char;
+
+	struct role_record {
+        bool can_login = false;
+        bool is_superuser = false;
+        std::unordered_set<role_name_t> member_of;
+        std::unordered_set<role_name_t> members;
+        sstring salted_hash;
+        std::unordered_map<sstring, sstring> attributes;
+        std::unordered_map<sstring, permission_set> permissions;
+        version_tag_t version; // used for seamless cache reloads
+    };
+
+    explicit cache(cql3::query_processor& qp) noexcept;
+    lw_shared_ptr<const role_record> get(const role_name_t& role) const noexcept;
+    future<> load_all();
+    future<> load_roles(std::unordered_set<role_name_t> roles);
+    static bool includes_table(const table_id&) noexcept;
+
+private:
+    using roles_map = absl::flat_hash_map<role_name_t, lw_shared_ptr<role_record>>;
+    roles_map _roles;
+    version_tag_t _current_version;
+    cql3::query_processor& _qp;
+
+    future<lw_shared_ptr<role_record>> fetch_role(const role_name_t& role) const;
+    future<> prune_all() noexcept;
+    future<> distribute_role(const role_name_t& name, const lw_shared_ptr<role_record> role);
+};
+
+} // namespace auth

auth/common.hh

@@ -48,6 +48,10 @@ extern constinit const std::string_view AUTH_PACKAGE_NAME;
 
 } // namespace meta
 
+constexpr std::string_view PERMISSIONS_CF = "role_permissions";
+constexpr std::string_view ROLE_MEMBERS_CF = "role_members";
+constexpr std::string_view ROLE_ATTRIBUTES_CF = "role_attributes";
+
 // This is a helper to check whether auth-v2 is on.
 bool legacy_mode(cql3::query_processor& qp);
 

auth/default_authorizer.cc

@@ -37,7 +37,6 @@ std::string_view default_authorizer::qualified_java_name() const {
 static constexpr std::string_view ROLE_NAME = "role";
 static constexpr std::string_view RESOURCE_NAME = "resource";
 static constexpr std::string_view PERMISSIONS_NAME = "permissions";
-static constexpr std::string_view PERMISSIONS_CF = "role_permissions";
 
 static logging::logger alogger("default_authorizer");
 

auth/ldap_role_manager.cc

@@ -83,17 +83,18 @@ static const class_registrator<
     ldap_role_manager,
     cql3::query_processor&,
     ::service::raft_group0_client&,
-    ::service::migration_manager&> registration(ldap_role_manager_full_name);
+    ::service::migration_manager&,
+    cache&> registration(ldap_role_manager_full_name);
 
 ldap_role_manager::ldap_role_manager(
         std::string_view query_template, std::string_view target_attr, std::string_view bind_name, std::string_view bind_password,
-        cql3::query_processor& qp, ::service::raft_group0_client& rg0c, ::service::migration_manager& mm)
+        cql3::query_processor& qp, ::service::raft_group0_client& rg0c, ::service::migration_manager& mm, cache& cache)
-        : _std_mgr(qp, rg0c, mm), _group0_client(rg0c), _query_template(query_template), _target_attr(target_attr), _bind_name(bind_name)
+        : _std_mgr(qp, rg0c, mm, cache), _group0_client(rg0c), _query_template(query_template), _target_attr(target_attr), _bind_name(bind_name)
         , _bind_password(bind_password)
         , _connection_factory(bind(std::mem_fn(&ldap_role_manager::reconnect), std::ref(*this))) {
 }
 
-ldap_role_manager::ldap_role_manager(cql3::query_processor& qp, ::service::raft_group0_client& rg0c, ::service::migration_manager& mm)
+ldap_role_manager::ldap_role_manager(cql3::query_processor& qp, ::service::raft_group0_client& rg0c, ::service::migration_manager& mm, cache& cache)
     : ldap_role_manager(
             qp.db().get_config().ldap_url_template(),
             qp.db().get_config().ldap_attr_role(),
@@ -101,7 +102,8 @@ ldap_role_manager::ldap_role_manager(cql3::query_processor& qp, ::service::raft_
             qp.db().get_config().ldap_bind_passwd(),
             qp,
             rg0c,
-            mm) {
+            mm,
+            cache) {
 }
 
 std::string_view ldap_role_manager::qualified_java_name() const noexcept {

auth/ldap_role_manager.hh

@@ -14,6 +14,7 @@
 
 #include "ent/ldap/ldap_connection.hh"
 #include "standard_role_manager.hh"
+#include "auth/cache.hh"
 
 namespace auth {
 
@@ -43,12 +44,13 @@ class ldap_role_manager : public role_manager {
             std::string_view bind_password, ///< LDAP bind credentials.
             cql3::query_processor& qp, ///< Passed to standard_role_manager.
             ::service::raft_group0_client& rg0c, ///< Passed to standard_role_manager.
-            ::service::migration_manager& mm ///< Passed to standard_role_manager.
+            ::service::migration_manager& mm, ///< Passed to standard_role_manager.
+            cache& cache ///< Passed to standard_role_manager.
     );
 
     /// Retrieves LDAP configuration entries from qp and invokes the other constructor.  Required by
     /// class_registrator<role_manager>.
-    ldap_role_manager(cql3::query_processor& qp, ::service::raft_group0_client& rg0c, ::service::migration_manager& mm);
+    ldap_role_manager(cql3::query_processor& qp, ::service::raft_group0_client& rg0c, ::service::migration_manager& mm, cache& cache);
 
     /// Thrown when query-template parsing fails.
     struct url_error : public std::runtime_error {

auth/maintenance_socket_role_manager.cc

@@ -11,6 +11,7 @@
 #include <seastar/core/future.hh>
 #include <stdexcept>
 #include <string_view>
+#include "auth/cache.hh"
 #include "cql3/description.hh"
 #include "utils/class_registrator.hh"
 
@@ -23,7 +24,8 @@ static const class_registrator<
         maintenance_socket_role_manager,
         cql3::query_processor&,
         ::service::raft_group0_client&,
-        ::service::migration_manager&> registration(sstring{maintenance_socket_role_manager_name});
+        ::service::migration_manager&,
+        cache&> registration(sstring{maintenance_socket_role_manager_name});
 
 
 std::string_view maintenance_socket_role_manager::qualified_java_name() const noexcept {

auth/maintenance_socket_role_manager.hh

@@ -8,6 +8,7 @@
 
 #pragma once
 
+#include "auth/cache.hh"
 #include "auth/resource.hh"
 #include "auth/role_manager.hh"
 #include <seastar/core/future.hh>
@@ -29,7 +30,7 @@ extern const std::string_view maintenance_socket_role_manager_name;
 // system_auth keyspace, which may be not yet created when the maintenance socket starts listening.
 class maintenance_socket_role_manager final : public role_manager {
 public:
-    maintenance_socket_role_manager(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&) {}
+    maintenance_socket_role_manager(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, cache&) {}
 
     virtual std::string_view qualified_java_name() const noexcept override;
 

auth/password_authenticator.cc

@@ -49,6 +49,7 @@ static const class_registrator<
         cql3::query_processor&,
         ::service::raft_group0_client&,
         ::service::migration_manager&,
+        cache&,
         utils::alien_worker&> password_auth_reg("org.apache.cassandra.auth.PasswordAuthenticator");
 
 static thread_local auto rng_for_salt = std::default_random_engine(std::random_device{}());
@@ -63,10 +64,11 @@ std::string password_authenticator::default_superuser(const db::config& cfg) {
 password_authenticator::~password_authenticator() {
 }
 
-password_authenticator::password_authenticator(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm, utils::alien_worker& hashing_worker)
+password_authenticator::password_authenticator(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm, cache& cache, utils::alien_worker& hashing_worker)
     : _qp(qp)
     , _group0_client(g0)
     , _migration_manager(mm)
+    , _cache(cache)
     , _stopped(make_ready_future<>()) 
     , _superuser(default_superuser(qp.db().get_config()))
     , _hashing_worker(hashing_worker)
@@ -315,11 +317,20 @@ future<authenticated_user> password_authenticator::authenticate(
     const sstring password = credentials.at(PASSWORD_KEY);
 
     try {
-        const std::optional<sstring> salted_hash = co_await get_password_hash(username);
+        std::optional<sstring> salted_hash;
+        if (legacy_mode(_qp)) {
+            salted_hash = co_await get_password_hash(username);
             if (!salted_hash) {
                 throw exceptions::authentication_exception("Username and/or password are incorrect");
             }
-        const bool password_match = co_await _hashing_worker.submit<bool>([password = std::move(password), salted_hash = std::move(salted_hash)]{
+        } else {
+            auto role = _cache.get(username);
+            if (!role || role->salted_hash.empty()) {
+                throw exceptions::authentication_exception("Username and/or password are incorrect");
+            }
+            salted_hash = role->salted_hash;
+        }
+        const bool password_match = co_await _hashing_worker.submit<bool>([password = std::move(password), salted_hash] {
             return passwords::check(password, *salted_hash);
         });
         if (!password_match) {

auth/password_authenticator.hh

@@ -16,6 +16,7 @@
 #include "db/consistency_level_type.hh"
 #include "auth/authenticator.hh"
 #include "auth/passwords.hh"
+#include "auth/cache.hh"
 #include "service/raft/raft_group0_client.hh"
 #include "utils/alien_worker.hh"
 
@@ -41,6 +42,7 @@ class password_authenticator : public authenticator {
     cql3::query_processor& _qp;
     ::service::raft_group0_client& _group0_client;
     ::service::migration_manager& _migration_manager;
+    cache& _cache;
     future<> _stopped;
     abort_source _as;
     std::string _superuser; // default superuser name from the config (may or may not be present in roles table)
@@ -53,7 +55,7 @@ public:
     static db::consistency_level consistency_for_user(std::string_view role_name);
     static std::string default_superuser(const db::config&);
 
-    password_authenticator(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, utils::alien_worker&);
+    password_authenticator(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, cache&, utils::alien_worker&);
 
     ~password_authenticator();
 

auth/saslauthd_authenticator.cc

@@ -35,9 +35,10 @@ static const class_registrator<
         cql3::query_processor&,
         ::service::raft_group0_client&,
         ::service::migration_manager&,
+        cache&,
         utils::alien_worker&> saslauthd_auth_reg("com.scylladb.auth.SaslauthdAuthenticator");
 
-saslauthd_authenticator::saslauthd_authenticator(cql3::query_processor& qp, ::service::raft_group0_client&, ::service::migration_manager&, utils::alien_worker&)
+saslauthd_authenticator::saslauthd_authenticator(cql3::query_processor& qp, ::service::raft_group0_client&, ::service::migration_manager&, cache&, utils::alien_worker&)
     : _socket_path(qp.db().get_config().saslauthd_socket_path())
 {}
 

auth/saslauthd_authenticator.hh

@@ -11,6 +11,7 @@
 #pragma once
 
 #include "auth/authenticator.hh"
+#include "auth/cache.hh"
 #include "utils/alien_worker.hh"
 
 namespace cql3 {
@@ -29,7 +30,7 @@ namespace auth {
 class saslauthd_authenticator : public authenticator {
     sstring _socket_path; ///< Path to the domain socket on which saslauthd is listening.
 public:
-    saslauthd_authenticator(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, utils::alien_worker&);
+    saslauthd_authenticator(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, cache&,utils::alien_worker&);
 
     future<> start() override;
 

auth/service.cc

@@ -17,6 +17,7 @@
 #include <chrono>
 
 #include <seastar/core/future-util.hh>
+#include <seastar/core/shard_id.hh>
 #include <seastar/core/sharded.hh>
 #include <seastar/core/shared_ptr.hh>
 
@@ -157,6 +158,7 @@ static future<> validate_role_exists(const service& ser, std::string_view role_n
 
 service::service(
         utils::loading_cache_config c,
+        cache& cache,
         cql3::query_processor& qp,
         ::service::raft_group0_client& g0,
         ::service::migration_notifier& mn,
@@ -166,6 +168,7 @@ service::service(
         maintenance_socket_enabled used_by_maintenance_socket)
             : _loading_cache_config(std::move(c))
             , _permissions_cache(nullptr)
+            , _cache(cache)
             , _qp(qp)
             , _group0_client(g0)
             , _mnotifier(mn)
@@ -188,15 +191,17 @@ service::service(
         ::service::migration_manager& mm,
         const service_config& sc,
         maintenance_socket_enabled used_by_maintenance_socket,
+        cache& cache,
         utils::alien_worker& hashing_worker)
             : service(
                       std::move(c),
+                      cache,
                       qp,
                       g0,
                       mn,
                       create_object<authorizer>(sc.authorizer_java_name, qp, g0, mm),
-                      create_object<authenticator>(sc.authenticator_java_name, qp, g0, mm, hashing_worker),
+                      create_object<authenticator>(sc.authenticator_java_name, qp, g0, mm, cache, hashing_worker),
-                      create_object<role_manager>(sc.role_manager_java_name, qp, g0, mm),
+                      create_object<role_manager>(sc.role_manager_java_name, qp, g0, mm, cache),
                       used_by_maintenance_socket) {
 }
 
@@ -232,6 +237,9 @@ future<> service::start(::service::migration_manager& mm, db::system_keyspace& s
     auto auth_version = co_await sys_ks.get_auth_version();
     // version is set in query processor to be easily available in various places we call auth::legacy_mode check.
     _qp.auth_version = auth_version;
+    if (this_shard_id() == 0) {
+        co_await _cache.load_all();
+    }
     if (!_used_by_maintenance_socket) {
         // this legacy keyspace is only used by cqlsh
         // it's needed when executing `list roles` or `list users`

auth/service.hh

@@ -21,6 +21,7 @@
 #include "auth/authorizer.hh"
 #include "auth/permission.hh"
 #include "auth/permissions_cache.hh"
+#include "auth/cache.hh"
 #include "auth/role_manager.hh"
 #include "auth/common.hh"
 #include "cql3/description.hh"
@@ -77,6 +78,7 @@ public:
 class service final : public seastar::peering_sharded_service<service> {
     utils::loading_cache_config _loading_cache_config;
     std::unique_ptr<permissions_cache> _permissions_cache;
+    cache& _cache;
 
     cql3::query_processor& _qp;
 
@@ -107,6 +109,7 @@ class service final : public seastar::peering_sharded_service<service> {
 public:
     service(
             utils::loading_cache_config,
+            cache& cache,
             cql3::query_processor&,
             ::service::raft_group0_client&,
             ::service::migration_notifier&,
@@ -128,6 +131,7 @@ public:
             ::service::migration_manager&,
             const service_config&,
             maintenance_socket_enabled,
+            cache&,
             utils::alien_worker&);
 
     future<> start(::service::migration_manager&, db::system_keyspace&);

auth/standard_role_manager.cc

@@ -41,21 +41,6 @@
 
 namespace auth {
 
-namespace meta {
-
-namespace role_members_table {
-
-constexpr std::string_view name{"role_members" , 12};
-
-}
-
-namespace role_attributes_table {
-
-constexpr std::string_view name{"role_attributes", 15};
-
-}
-
-}
 
 static logging::logger log("standard_role_manager");
 
@@ -64,7 +49,8 @@ static const class_registrator<
         standard_role_manager,
         cql3::query_processor&,
         ::service::raft_group0_client&,
-        ::service::migration_manager&> registration("org.apache.cassandra.auth.CassandraRoleManager");
+        ::service::migration_manager&,
+        cache&> registration("org.apache.cassandra.auth.CassandraRoleManager");
 
 struct record final {
     sstring name;
@@ -121,10 +107,11 @@ static bool has_can_login(const cql3::untyped_result_set_row& row) {
     return row.has("can_login") && !(boolean_type->deserialize(row.get_blob_unfragmented("can_login")).is_null());
 }
 
-standard_role_manager::standard_role_manager(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm)
+standard_role_manager::standard_role_manager(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm, cache& cache)
     : _qp(qp)
     , _group0_client(g0)
     , _migration_manager(mm)
+    , _cache(cache)
     , _stopped(make_ready_future<>())
     , _superuser(password_authenticator::default_superuser(qp.db().get_config()))
 {}
@@ -136,7 +123,7 @@ std::string_view standard_role_manager::qualified_java_name() const noexcept {
 const resource_set& standard_role_manager::protected_resources() const {
     static const resource_set resources({
             make_data_resource(meta::legacy::AUTH_KS, meta::roles_table::name),
-            make_data_resource(meta::legacy::AUTH_KS, meta::role_members_table::name)});
+            make_data_resource(meta::legacy::AUTH_KS, ROLE_MEMBERS_CF)});
 
     return resources;
 }
@@ -160,7 +147,7 @@ future<> standard_role_manager::create_legacy_metadata_tables_if_missing() const
             "  PRIMARY KEY (role, member)"
             ")",
             meta::legacy::AUTH_KS,
-            meta::role_members_table::name);
+            ROLE_MEMBERS_CF);
     static const sstring create_role_attributes_query = seastar::format(
             "CREATE TABLE {}.{} ("
             "  role text,"
@@ -169,7 +156,7 @@ future<> standard_role_manager::create_legacy_metadata_tables_if_missing() const
             "  PRIMARY KEY(role, name)"
             ")",
             meta::legacy::AUTH_KS,
-            meta::role_attributes_table::name);
+            ROLE_ATTRIBUTES_CF);
     return when_all_succeed(
             create_legacy_metadata_table_if_missing(
                     meta::roles_table::name,
@@ -177,12 +164,12 @@ future<> standard_role_manager::create_legacy_metadata_tables_if_missing() const
                     create_roles_query,
                     _migration_manager),
             create_legacy_metadata_table_if_missing(
-                    meta::role_members_table::name,
+                    ROLE_MEMBERS_CF,
                     _qp,
                     create_role_members_query,
                     _migration_manager),
             create_legacy_metadata_table_if_missing(
-                    meta::role_attributes_table::name,
+                    ROLE_ATTRIBUTES_CF,
                     _qp,
                     create_role_attributes_query,
                     _migration_manager)).discard_result();
@@ -429,7 +416,7 @@ future<> standard_role_manager::drop(std::string_view role_name, ::service::grou
     const auto revoke_from_members = [this, role_name, &mc] () -> future<> {
         const sstring query = seastar::format("SELECT member FROM {}.{} WHERE role = ?",
                 get_auth_ks_name(_qp),
-                meta::role_members_table::name);
+                ROLE_MEMBERS_CF);
         const auto members = co_await _qp.execute_internal(
                 query,
                 consistency_for_role(role_name),
@@ -461,7 +448,7 @@ future<> standard_role_manager::drop(std::string_view role_name, ::service::grou
     const auto remove_attributes_of = [this, role_name, &mc] () -> future<> {
         const sstring query = seastar::format("DELETE FROM {}.{} WHERE role = ?",
                 get_auth_ks_name(_qp),
-                meta::role_attributes_table::name);
+                ROLE_ATTRIBUTES_CF);
         if (legacy_mode(_qp)) {
             co_await _qp.execute_internal(query, {sstring(role_name)},
                 cql3::query_processor::cache_internal::yes).discard_result();
@@ -517,7 +504,7 @@ standard_role_manager::legacy_modify_membership(
             case membership_change::add: {
                 const sstring insert_query = seastar::format("INSERT INTO {}.{} (role, member) VALUES (?, ?)",
                         get_auth_ks_name(_qp),
-                        meta::role_members_table::name);
+                        ROLE_MEMBERS_CF);
                 co_return co_await _qp.execute_internal(
                         insert_query,
                         consistency_for_role(role_name),
@@ -529,7 +516,7 @@ standard_role_manager::legacy_modify_membership(
             case membership_change::remove: {
                 const sstring delete_query = seastar::format("DELETE FROM {}.{} WHERE role = ? AND member = ?",
                         get_auth_ks_name(_qp),
-                        meta::role_members_table::name);
+                        ROLE_MEMBERS_CF);
                 co_return co_await _qp.execute_internal(
                         delete_query,
                         consistency_for_role(role_name),
@@ -567,12 +554,12 @@ standard_role_manager::modify_membership(
     case membership_change::add:
         modify_role_members = seastar::format("INSERT INTO {}.{} (role, member) VALUES (?, ?)",
                 get_auth_ks_name(_qp),
-                meta::role_members_table::name);
+                ROLE_MEMBERS_CF);
         break;
     case membership_change::remove:
         modify_role_members = seastar::format("DELETE FROM {}.{} WHERE role = ? AND member = ?",
                 get_auth_ks_name(_qp),
-                meta::role_members_table::name);
+                ROLE_MEMBERS_CF);
         break;
     default:
         on_internal_error(log, format("unknown membership_change value: {}", int(ch)));
@@ -666,7 +653,7 @@ future<role_set> standard_role_manager::query_granted(std::string_view grantee_n
 future<role_to_directly_granted_map> standard_role_manager::query_all_directly_granted(::service::query_state& qs) {
     const sstring query = seastar::format("SELECT * FROM {}.{}",
             get_auth_ks_name(_qp),
-            meta::role_members_table::name);
+            ROLE_MEMBERS_CF);
 
     const auto results = co_await _qp.execute_internal(
             query,
@@ -731,15 +718,21 @@ future<bool> standard_role_manager::is_superuser(std::string_view role_name) {
 }
 
 future<bool> standard_role_manager::can_login(std::string_view role_name) {
-    return require_record(_qp, role_name).then([](record r) {
+    if (legacy_mode(_qp)) {
-        return r.can_login;
+       const auto r = co_await require_record(_qp, role_name);
-    });
+       co_return r.can_login;
+    }
+    auto role = _cache.get(sstring(role_name));
+    if (!role) {
+        throw nonexistant_role(role_name);
+    }
+    co_return role->can_login;
 }
 
 future<std::optional<sstring>> standard_role_manager::get_attribute(std::string_view role_name, std::string_view attribute_name, ::service::query_state& qs) {
     const sstring query = seastar::format("SELECT name, value FROM {}.{} WHERE role = ? AND name = ?",
             get_auth_ks_name(_qp),
-            meta::role_attributes_table::name);
+            ROLE_ATTRIBUTES_CF);
     const auto result_set = co_await _qp.execute_internal(query, db::consistency_level::ONE, qs, {sstring(role_name), sstring(attribute_name)}, cql3::query_processor::cache_internal::yes);
     if (!result_set->empty()) {
         const cql3::untyped_result_set_row &row = result_set->one();
@@ -770,7 +763,7 @@ future<> standard_role_manager::set_attribute(std::string_view role_name, std::s
     }
     const sstring query = seastar::format("INSERT INTO {}.{} (role, name, value)  VALUES (?, ?, ?)",
             get_auth_ks_name(_qp),
-            meta::role_attributes_table::name);
+            ROLE_ATTRIBUTES_CF);
     if (legacy_mode(_qp)) {
         co_await _qp.execute_internal(query, {sstring(role_name), sstring(attribute_name), sstring(attribute_value)}, cql3::query_processor::cache_internal::yes).discard_result();
     } else {
@@ -785,7 +778,7 @@ future<> standard_role_manager::remove_attribute(std::string_view role_name, std
     }
     const sstring query = seastar::format("DELETE FROM {}.{} WHERE role = ? AND name = ?",
             get_auth_ks_name(_qp),
-            meta::role_attributes_table::name);
+            ROLE_ATTRIBUTES_CF);
     if (legacy_mode(_qp)) {
         co_await _qp.execute_internal(query, {sstring(role_name), sstring(attribute_name)}, cql3::query_processor::cache_internal::yes).discard_result();
     } else {

auth/standard_role_manager.hh

@@ -10,6 +10,7 @@
 
 #include "auth/common.hh"
 #include "auth/role_manager.hh"
+#include "auth/cache.hh"
 
 #include <string_view>
 
@@ -36,13 +37,14 @@ class standard_role_manager final : public role_manager {
     cql3::query_processor& _qp;
     ::service::raft_group0_client& _group0_client;
     ::service::migration_manager& _migration_manager;
+    cache& _cache;
     future<> _stopped;
     abort_source _as;
     std::string _superuser;
     shared_promise<> _superuser_created_promise;
 
 public:
-    standard_role_manager(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&);
+    standard_role_manager(cql3::query_processor&, ::service::raft_group0_client&, ::service::migration_manager&, cache&);
 
     virtual std::string_view qualified_java_name() const noexcept override;
 

auth/transitional.cc

@@ -13,6 +13,7 @@
 #include "auth/authorizer.hh"
 #include "auth/default_authorizer.hh"
 #include "auth/password_authenticator.hh"
+#include "auth/cache.hh"
 #include "auth/permission.hh"
 #include "service/raft/raft_group0_client.hh"
 #include "utils/class_registrator.hh"
@@ -37,8 +38,8 @@ class transitional_authenticator : public authenticator {
 public:
     static const sstring PASSWORD_AUTHENTICATOR_NAME;
 
-    transitional_authenticator(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm, utils::alien_worker& hashing_worker)
+    transitional_authenticator(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm, cache& cache, utils::alien_worker& hashing_worker)
-            : transitional_authenticator(std::make_unique<password_authenticator>(qp, g0, mm, hashing_worker)) {
+            : transitional_authenticator(std::make_unique<password_authenticator>(qp, g0, mm, cache, hashing_worker)) {
     }
     transitional_authenticator(std::unique_ptr<authenticator> a)
             : _authenticator(std::move(a)) {
@@ -240,6 +241,7 @@ static const class_registrator<
         cql3::query_processor&,
         ::service::raft_group0_client&,
         ::service::migration_manager&,
+        auth::cache&,
         utils::alien_worker&> transitional_authenticator_reg(auth::PACKAGE_NAME + "TransitionalAuthenticator");
 
 static const class_registrator<

backlog_controller.hh

@@ -15,6 +15,7 @@
 #include <cmath>
 
 #include "seastarx.hh"
+#include "backlog_controller_fwd.hh"
 
 // Simple proportional controller to adjust shares for processes for which a backlog can be clearly
 // defined.
@@ -128,11 +129,21 @@ public:
     static constexpr unsigned normalization_factor = 30;
     static constexpr float disable_backlog = std::numeric_limits<double>::infinity();
     static constexpr float backlog_disabled(float backlog) { return std::isinf(backlog); }
-    compaction_controller(backlog_controller::scheduling_group sg, float static_shares, std::chrono::milliseconds interval, std::function<float()> current_backlog)
+    static inline const std::vector<backlog_controller::control_point> default_control_points = {
+            backlog_controller::control_point{0.0, 50}, {1.5, 100}, {normalization_factor, default_compaction_maximum_shares}};
+    compaction_controller(backlog_controller::scheduling_group sg, float static_shares, std::optional<float> max_shares,
+        std::chrono::milliseconds interval, std::function<float()> current_backlog)
         : backlog_controller(std::move(sg), std::move(interval),
-          std::vector<backlog_controller::control_point>({{0.0, 50}, {1.5, 100} , {normalization_factor, 1000}}),
+          default_control_points,
           std::move(current_backlog),
           static_shares
         )
-    {}
+    {
+        if (max_shares) {
+            set_max_shares(*max_shares);
+        }
+    }
+
+    // Updates the maximum output value for control points.
+    void set_max_shares(float max_shares);
 };

backlog_controller_fwd.hh

@@ -0,0 +1,13 @@
+/*
+ * Copyright (C) 2025-present ScyllaDB
+ */
+
+/*
+ * SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
+ */
+
+#pragma once
+
+#include <cstdint>
+
+static constexpr uint64_t default_compaction_maximum_shares = 1000;

cdc/CMakeLists.txt

@@ -17,5 +17,8 @@ target_link_libraries(cdc
   PRIVATE
     replica)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(cdc REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers cdc
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

cdc/log.cc

@@ -25,6 +25,7 @@
 #include "locator/abstract_replication_strategy.hh"
 #include "locator/topology.hh"
 #include "replica/database.hh"
+#include "db/config.hh"
 #include "db/schema_tables.hh"
 #include "gms/feature_service.hh"
 #include "schema/schema.hh"
@@ -586,11 +587,9 @@ bytes log_data_column_deleted_elements_name_bytes(const bytes& column_name) {
     return to_bytes(cdc_deleted_elements_column_prefix) + column_name;
 }
 
-static schema_ptr create_log_schema(const schema& s, const replica::database& db,
+static void set_default_properties_log_table(schema_builder& b, const schema& s,
-        const keyspace_metadata& ksm, api::timestamp_type timestamp, std::optional<table_id> uuid, schema_ptr old)
+        const replica::database& db, const keyspace_metadata& ksm)
 {
-    schema_builder b(s.ks_name(), log_name(s.cf_name()));
-    b.with_partitioner(cdc::cdc_partitioner::classname);
     b.set_compaction_strategy(compaction::compaction_strategy_type::time_window);
     b.set_comment(fmt::format("CDC log for {}.{}", s.ks_name(), s.cf_name()));
     auto ttl_seconds = s.cdc_options().ttl();
@@ -616,13 +615,22 @@ static schema_ptr create_log_schema(const schema& s, const replica::database& db
                         std::to_string(std::max(1, window_seconds / 2))},
         });
     }
+    b.set_caching_options(caching_options::get_disabled_caching_options());
+
+    auto rs = generate_replication_strategy(ksm, db.get_token_metadata().get_topology());
+    auto tombstone_gc_ext = seastar::make_shared<tombstone_gc_extension>(get_default_tombstone_gc_mode(*rs, db.get_token_metadata(), false));
+    b.add_extension(tombstone_gc_extension::NAME, std::move(tombstone_gc_ext));
+}
+
+static void add_columns_to_cdc_log(schema_builder& b, const schema& s,
+        const api::timestamp_type timestamp, const schema_ptr old)
+{
     b.with_column(log_meta_column_name_bytes("stream_id"), bytes_type, column_kind::partition_key);
     b.with_column(log_meta_column_name_bytes("time"), timeuuid_type, column_kind::clustering_key);
     b.with_column(log_meta_column_name_bytes("batch_seq_no"), int32_type, column_kind::clustering_key);
     b.with_column(log_meta_column_name_bytes("operation"), data_type_for<operation_native_type>());
     b.with_column(log_meta_column_name_bytes("ttl"), long_type);
     b.with_column(log_meta_column_name_bytes("end_of_batch"), boolean_type);
-    b.set_caching_options(caching_options::get_disabled_caching_options());
 
     auto validate_new_column = [&] (const sstring& name) {
         // When dropping a column from a CDC log table, we set the drop timestamp to be
@@ -692,15 +700,28 @@ static schema_ptr create_log_schema(const schema& s, const replica::database& db
     add_columns(s.clustering_key_columns());
     add_columns(s.static_columns(), true);
     add_columns(s.regular_columns(), true);
+}
+
+static schema_ptr create_log_schema(const schema& s, const replica::database& db,
+        const keyspace_metadata& ksm, api::timestamp_type timestamp, std::optional<table_id> uuid, schema_ptr old)
+{
+    schema_builder b(s.ks_name(), log_name(s.cf_name()));
+
+    b.with_partitioner(cdc::cdc_partitioner::classname);
+
+    if (old) {
+        // If the user reattaches the log table, do not change its properties.
+        b.set_properties(old->get_properties());
+    } else {
+        set_default_properties_log_table(b, s, db, ksm);
+    }
+
+    add_columns_to_cdc_log(b, s, timestamp, old);
 
     if (uuid) {
         b.set_uuid(*uuid);
     }
 
-    auto rs = generate_replication_strategy(ksm, db.get_token_metadata().get_topology());
-    auto tombstone_gc_ext = seastar::make_shared<tombstone_gc_extension>(get_default_tombstone_gc_mode(*rs, db.get_token_metadata()));
-    b.add_extension(tombstone_gc_extension::NAME, std::move(tombstone_gc_ext));
-
     /**
      * #10473 - if we are redefining the log table, we need to ensure any dropped
      * columns are registered in "dropped_columns" table, otherwise clients will not
@@ -931,9 +952,6 @@ static managed_bytes merge(const abstract_type& type, const managed_bytes_opt& p
     throw std::runtime_error(format("cdc merge: unknown type {}", type.name()));
 }
 
-using cell_map = std::unordered_map<const column_definition*, managed_bytes_opt>;
-using row_states_map = std::unordered_map<clustering_key, cell_map, clustering_key::hashing, clustering_key::equality>;
-
 static managed_bytes_opt get_col_from_row_state(const cell_map* state, const column_definition& cdef) {
     if (state) {
         if (auto it = state->find(&cdef); it != state->end()) {
@@ -943,7 +961,12 @@ static managed_bytes_opt get_col_from_row_state(const cell_map* state, const col
     return std::nullopt;
 }
 
-static cell_map* get_row_state(row_states_map& row_states, const clustering_key& ck) {
+cell_map* get_row_state(row_states_map& row_states, const clustering_key& ck) {
+    auto it = row_states.find(ck);
+    return it == row_states.end() ? nullptr : &it->second;
+}
+
+const cell_map* get_row_state(const row_states_map& row_states, const clustering_key& ck) {
     auto it = row_states.find(ck);
     return it == row_states.end() ? nullptr : &it->second;
 }
@@ -1413,6 +1436,8 @@ struct process_change_visitor {
     row_states_map& _clustering_row_states;
     cell_map& _static_row_state;
 
+    const bool _is_update = false;
+
     const bool _generate_delta_values = true;
 
     void static_row_cells(auto&& visit_row_cells) {
@@ -1436,12 +1461,13 @@ struct process_change_visitor {
 
         struct clustering_row_cells_visitor : public process_row_visitor {
             operation _cdc_op = operation::update;
+            operation _marker_op = operation::insert;
 
             using process_row_visitor::process_row_visitor;
 
             void marker(const row_marker& rm) {
                 _ttl_column = get_ttl(rm);
-                _cdc_op = operation::insert;
+                _cdc_op = _marker_op;
             }
         };
 
@@ -1449,6 +1475,9 @@ struct process_change_visitor {
                 log_ck, _touched_parts, _builder,
                 _enable_updating_state, &ckey, get_row_state(_clustering_row_states, ckey),
                 _clustering_row_states, _generate_delta_values);
+        if (_is_update && _request_options.alternator) {
+            v._marker_op = operation::update;
+        }
         visit_row_cells(v);
 
         if (_enable_updating_state) {
@@ -1602,6 +1631,11 @@ private:
 
     row_states_map _clustering_row_states;
     cell_map _static_row_state;
+    // True if the mutated row existed before applying the mutation. In other
+    // words, if the preimage is enabled and it isn't empty (otherwise, we
+    // assume that the row is non-existent). Used for Alternator Streams (see
+    // #6918).
+    bool _is_update = false;
 
     const bool _uses_tablets;
 
@@ -1728,6 +1762,7 @@ public:
             ._enable_updating_state = _enable_updating_state,
             ._clustering_row_states = _clustering_row_states,
             ._static_row_state = _static_row_state,
+            ._is_update = _is_update,
             ._generate_delta_values = generate_delta_values(_builder->base_schema())
         };
         cdc::inspect_mutation(m, v);
@@ -1738,6 +1773,10 @@ public:
         _builder->end_record();
     }
 
+    const row_states_map& clustering_row_states() const override {
+        return _clustering_row_states;
+    }
+
     // Takes and returns generated cdc log mutations and associated statistics about parts touched during transformer's lifetime.
     // The `transformer` object on which this method was called on should not be used anymore.
     std::tuple<utils::chunked_vector<mutation>, stats::part_type_set> finish() && {
@@ -1861,6 +1900,7 @@ public:
                     _static_row_state[&c] = std::move(*maybe_cell_view);
                 }
             }
+            _is_update = true;
         }
 
         if (static_only) {
@@ -1948,6 +1988,7 @@ cdc::cdc_service::impl::augment_mutation_call(lowres_clock::time_point timeout,
                 return make_ready_future<>();
             }
 
+            const bool alternator_increased_compatibility = options.alternator && options.alternator_streams_increased_compatibility;
             transformer trans(_ctxt, s, m.decorated_key(), options);
 
             auto f = make_ready_future<lw_shared_ptr<cql3::untyped_result_set>>(nullptr);
@@ -1955,7 +1996,7 @@ cdc::cdc_service::impl::augment_mutation_call(lowres_clock::time_point timeout,
                 // Preimage has been fetched by upper layers.
                 tracing::trace(tr_state, "CDC: Using a prefetched preimage");
                 f = make_ready_future<lw_shared_ptr<cql3::untyped_result_set>>(options.preimage);
-            } else if (s->cdc_options().preimage() || s->cdc_options().postimage()) {
+            } else if (s->cdc_options().preimage() || s->cdc_options().postimage() || alternator_increased_compatibility) {
                 // Note: further improvement here would be to coalesce the pre-image selects into one
                 // if a batch contains several modifications to the same table. Otoh, batch is rare(?)
                 // so this is premature.
@@ -1972,7 +2013,7 @@ cdc::cdc_service::impl::augment_mutation_call(lowres_clock::time_point timeout,
                 tracing::trace(tr_state, "CDC: Preimage not enabled for the table, not querying current value of {}", m.decorated_key());
             }
 
-            return f.then([trans = std::move(trans), &mutations, idx, tr_state, &details] (lw_shared_ptr<cql3::untyped_result_set> rs) mutable {
+            return f.then([alternator_increased_compatibility, trans = std::move(trans), &mutations, idx, tr_state, &details, &options] (lw_shared_ptr<cql3::untyped_result_set> rs) mutable {
                 auto& m = mutations[idx];
                 auto& s = m.schema();
 
@@ -1987,13 +2028,13 @@ cdc::cdc_service::impl::augment_mutation_call(lowres_clock::time_point timeout,
                 details.had_preimage |= preimage;
                 details.had_postimage |= postimage;
                 tracing::trace(tr_state, "CDC: Generating log mutations for {}", m.decorated_key());
-                if (should_split(m)) {
+                if (should_split(m, options)) {
                     tracing::trace(tr_state, "CDC: Splitting {}", m.decorated_key());
                     details.was_split = true;
-                    process_changes_with_splitting(m, trans, preimage, postimage);
+                    process_changes_with_splitting(m, trans, preimage, postimage, alternator_increased_compatibility);
                 } else {
                     tracing::trace(tr_state, "CDC: No need to split {}", m.decorated_key());
-                    process_changes_without_splitting(m, trans, preimage, postimage);
+                    process_changes_without_splitting(m, trans, preimage, postimage, alternator_increased_compatibility);
                 }
                 auto [log_mut, touched_parts] = std::move(trans).finish();
                 const int generated_count = log_mut.size();

cdc/log.hh

@@ -52,6 +52,9 @@ class database;
 
 namespace cdc {
 
+using cell_map = std::unordered_map<const column_definition*, managed_bytes_opt>;
+using row_states_map = std::unordered_map<clustering_key, cell_map, clustering_key::hashing, clustering_key::equality>;
+
 // cdc log table operation
 enum class operation : int8_t {
     // note: these values will eventually be read by a third party, probably not privvy to this
@@ -73,6 +76,14 @@ struct per_request_options {
     // Scylla. Currently, only TTL expiration implementation for Alternator
     // uses this.
     const bool is_system_originated = false;
+    // True if this mutation was emitted by Alternator.
+    const bool alternator = false;
+    // Sacrifice performance for the sake of better compatibility with DynamoDB
+    // Streams. It's important for correctness that
+    // alternator_streams_increased_compatibility config flag be read once per
+    // request, because it's live-updateable. As a result, the flag may change
+    // between reads.
+    const bool alternator_streams_increased_compatibility = false;
 };
 
 struct operation_result_tracker;
@@ -142,4 +153,7 @@ bool is_cdc_metacolumn_name(const sstring& name);
 
 utils::UUID generate_timeuuid(api::timestamp_type t);
 
+cell_map* get_row_state(row_states_map& row_states, const clustering_key& ck);
+const cell_map* get_row_state(const row_states_map& row_states, const clustering_key& ck);
+
 } // namespace cdc

cdc/split.cc

@@ -6,15 +6,28 @@
  * SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
  */
 
+#include "bytes.hh"
+#include "bytes_fwd.hh"
+#include "mutation/atomic_cell.hh"
+#include "mutation/atomic_cell_or_collection.hh"
+#include "mutation/collection_mutation.hh"
 #include "mutation/mutation.hh"
+#include "mutation/tombstone.hh"
 #include "schema/schema.hh"
 
+#include "seastar/core/sstring.hh"
 #include "types/concrete_types.hh"
+#include "types/types.hh"
 #include "types/user.hh"
 
 #include "split.hh"
 #include "log.hh"
 #include "change_visitor.hh"
+#include "utils/managed_bytes.hh"
+#include <string_view>
+#include <unordered_map>
+
+extern logging::logger cdc_log;
 
 struct atomic_column_update {
     column_id id;
@@ -490,6 +503,8 @@ struct should_split_visitor {
     // Otherwise we store the change's ttl.
     std::optional<gc_clock::duration> _ttl = std::nullopt;
 
+    virtual ~should_split_visitor() = default;
+
     inline bool finished() const { return _result; }
     inline void stop() { _result = true; }
 
@@ -512,7 +527,7 @@ struct should_split_visitor {
 
     void collection_tombstone(const tombstone& t) { visit(t.timestamp + 1); }
 
-    void live_collection_cell(bytes_view, const atomic_cell_view& cell) {
+    virtual void live_collection_cell(bytes_view, const atomic_cell_view& cell) {
         if (_had_row_marker) {
             // nonatomic updates cannot be expressed with an INSERT.
             return stop();
@@ -522,7 +537,7 @@ struct should_split_visitor {
     void dead_collection_cell(bytes_view, const atomic_cell_view& cell) { visit(cell); }
     void collection_column(const column_definition&, auto&& visit_collection) { visit_collection(*this); }
 
-    void marker(const row_marker& rm) {
+    virtual void marker(const row_marker& rm) {
         _had_row_marker = true;
         visit(rm.timestamp(), get_ttl(rm));
     }
@@ -563,7 +578,29 @@ struct should_split_visitor {
     }
 };
 
-bool should_split(const mutation& m) {
+// This is the same as the above, but it doesn't split a row marker away from
+// an update. As a result, updates that create an item appear as a single log
+// row.
+class alternator_should_split_visitor : public should_split_visitor {
+public:
+    ~alternator_should_split_visitor() override = default;
+
+    void live_collection_cell(bytes_view, const atomic_cell_view& cell) override {
+        visit(cell.timestamp());
+    }
+
+    void marker(const row_marker& rm) override {
+        visit(rm.timestamp());
+    }
+};
+
+bool should_split(const mutation& m, const per_request_options& options) {
+    if (options.alternator) {
+        alternator_should_split_visitor v;
+        cdc::inspect_mutation(m, v);
+        return v._result || v._ts == api::missing_timestamp;
+    }
+
     should_split_visitor v;
 
     cdc::inspect_mutation(m, v);
@@ -573,8 +610,109 @@ bool should_split(const mutation& m) {
         || v._ts == api::missing_timestamp;
 }
 
+// Returns true if the row state and the atomic and nonatomic entries represent
+// an equivalent item.
+static bool entries_match_row_state(const schema_ptr& base_schema, const cell_map& row_state, const std::vector<atomic_column_update>& atomic_entries,
+        std::vector<nonatomic_column_update>& nonatomic_entries) {
+    for (const auto& update : atomic_entries) {
+        const column_definition& cdef = base_schema->column_at(column_kind::regular_column, update.id);
+        const auto it = row_state.find(&cdef);
+        if (it == row_state.end()) {
+            return false;
+        }
+        if (to_managed_bytes_opt(update.cell.value().linearize()) != it->second) {
+            return false;
+        }
+    }
+    if (nonatomic_entries.empty()) {
+        return true;
+    }
+
+    for (const auto& update : nonatomic_entries) {
+        const column_definition& cdef = base_schema->column_at(column_kind::regular_column, update.id);
+        const auto it = row_state.find(&cdef);
+        if (it == row_state.end()) {
+            return false;
+        }
+
+        // The only collection used by Alternator is a non-frozen map.
+        auto current_raw_map = cdef.type->deserialize(*it->second);
+        map_type_impl::native_type current_values = value_cast<map_type_impl::native_type>(current_raw_map);
+
+        if (current_values.size() != update.cells.size()) {
+            return false;
+        }
+        
+        std::unordered_map<sstring_view, bytes> current_values_map;
+        for (const auto& entry : current_values) {
+            const auto attr_name = std::string_view(value_cast<sstring>(entry.first));
+            current_values_map[attr_name] = value_cast<bytes>(entry.second);
+        }
+
+        for (const auto& [key, value] : update.cells) {
+            const auto key_str = to_string_view(key);
+            if (!value.is_live()) {
+                if (current_values_map.contains(key_str)) {
+                    return false;
+                }
+            } else if (current_values_map[key_str] != value.value().linearize()) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+bool should_skip(batch& changes, const mutation& base_mutation, change_processor& processor) {
+    const schema_ptr& base_schema = base_mutation.schema();
+    // Alternator doesn't use static updates and clustered range deletions.
+    if (!changes.static_updates.empty() || !changes.clustered_range_deletions.empty()) {
+        return false;
+    }
+
+    for (clustered_row_insert& u : changes.clustered_inserts) {
+        const cell_map* row_state = get_row_state(processor.clustering_row_states(), u.key);
+        if (!row_state) {
+            return false;
+        }
+        if (!entries_match_row_state(base_schema, *row_state, u.atomic_entries, u.nonatomic_entries)) {
+            return false;
+        }
+    }
+
+    for (clustered_row_update& u : changes.clustered_updates) {
+        const cell_map* row_state = get_row_state(processor.clustering_row_states(), u.key);
+        if (!row_state) {
+            return false;
+        }
+        if (!entries_match_row_state(base_schema, *row_state, u.atomic_entries, u.nonatomic_entries)) {
+            return false;
+        }
+    }
+
+    // Skip only if the row being deleted does not exist (i.e. the deletion is a no-op).
+    for (const auto& row_deletion : changes.clustered_row_deletions) {
+        if (processor.clustering_row_states().contains(row_deletion.key)) {
+            return false;
+        }
+    }
+
+    // Don't skip if the item exists.
+    //
+    // Increased DynamoDB Streams compatibility guarantees that single-item
+    // operations will read the item and store it in the clustering row states.
+    // If it is not found there, we may skip CDC. This is safe as long as the
+    // assumptions of this operation's write isolation are not violated.
+    if (changes.partition_deletions && processor.clustering_row_states().contains(clustering_key::make_empty())) {
+        return false;
+    }
+
+    cdc_log.trace("Skipping CDC log for mutation {}", base_mutation);
+    return true;
+}
+
 void process_changes_with_splitting(const mutation& base_mutation, change_processor& processor,
-        bool enable_preimage, bool enable_postimage) {
+        bool enable_preimage, bool enable_postimage, bool alternator_strict_compatibility) {
     const auto base_schema = base_mutation.schema();
     auto changes = extract_changes(base_mutation);
     auto pk = base_mutation.key();
@@ -586,9 +724,6 @@ void process_changes_with_splitting(const mutation& base_mutation, change_proces
     const auto last_timestamp = changes.rbegin()->first;
 
     for (auto& [change_ts, btch] : changes) {
-        const bool is_last = change_ts == last_timestamp;
-        processor.begin_timestamp(change_ts, is_last);
-
         clustered_column_set affected_clustered_columns_per_row{clustering_key::less_compare(*base_schema)};
         one_kind_column_set affected_static_columns{base_schema->static_columns_count()};
 
@@ -597,6 +732,12 @@ void process_changes_with_splitting(const mutation& base_mutation, change_proces
             affected_clustered_columns_per_row = btch.get_affected_clustered_columns_per_row(*base_mutation.schema());
         }
 
+        if (alternator_strict_compatibility && should_skip(btch, base_mutation, processor)) {
+            continue;
+        }
+
+        const bool is_last = change_ts == last_timestamp;
+        processor.begin_timestamp(change_ts, is_last);
         if (enable_preimage) {
             if (affected_static_columns.count() > 0) {
                 processor.produce_preimage(nullptr, affected_static_columns);
@@ -684,7 +825,13 @@ void process_changes_with_splitting(const mutation& base_mutation, change_proces
 }
 
 void process_changes_without_splitting(const mutation& base_mutation, change_processor& processor,
-        bool enable_preimage, bool enable_postimage) {
+        bool enable_preimage, bool enable_postimage, bool alternator_strict_compatibility) {
+    if (alternator_strict_compatibility) {
+        auto changes = extract_changes(base_mutation);
+        if (should_skip(changes.begin()->second, base_mutation, processor)) {
+            return;
+        }
+    }
     auto ts = find_timestamp(base_mutation);
     processor.begin_timestamp(ts, true);
 

cdc/split.hh

@@ -9,6 +9,7 @@
 #pragma once
 
 #include <boost/dynamic_bitset.hpp>  // IWYU pragma: keep
+#include "cdc/log.hh"
 #include "replica/database_fwd.hh"
 #include "mutation/timestamp.hh"
 
@@ -65,12 +66,14 @@ public:
     // Tells processor we have reached end of record - last part
     // of a given timestamp batch
     virtual void end_record() = 0;
+
+    virtual const row_states_map& clustering_row_states() const = 0;
 };
 
-bool should_split(const mutation& base_mutation);
+bool should_split(const mutation& base_mutation, const per_request_options& options);
 void process_changes_with_splitting(const mutation& base_mutation, change_processor& processor,
-        bool enable_preimage, bool enable_postimage);
+        bool enable_preimage, bool enable_postimage, bool alternator_strict_compatibility);
 void process_changes_without_splitting(const mutation& base_mutation, change_processor& processor,
-        bool enable_preimage, bool enable_postimage);
+        bool enable_preimage, bool enable_postimage, bool alternator_strict_compatibility);
 
 }

compaction/CMakeLists.txt

@@ -21,5 +21,8 @@ target_link_libraries(compaction
     mutation_writer
     replica)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(compaction REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers compaction
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

compaction/compaction_manager.cc

@@ -867,8 +867,8 @@ auto fmt::formatter<compaction::compaction_task_executor>::format(const compacti
 
 namespace compaction {
 
-inline compaction_controller make_compaction_controller(const compaction_manager::scheduling_group& csg, uint64_t static_shares, std::function<double()> fn) {
+inline compaction_controller make_compaction_controller(const compaction_manager::scheduling_group& csg, uint64_t static_shares, std::optional<float> max_shares, std::function<double()> fn) {
-    return compaction_controller(csg, static_shares, 250ms, std::move(fn));
+    return compaction_controller(csg, static_shares, max_shares, 250ms, std::move(fn));
 }
 
 compaction::compaction_state::~compaction_state() {
@@ -1014,7 +1014,7 @@ compaction_manager::compaction_manager(config cfg, abort_source& as, tasks::task
     , _sys_ks("compaction_manager::system_keyspace")
     , _cfg(std::move(cfg))
     , _compaction_submission_timer(compaction_sg(), compaction_submission_callback())
-    , _compaction_controller(make_compaction_controller(compaction_sg(), static_shares(), [this] () -> float {
+    , _compaction_controller(make_compaction_controller(compaction_sg(), static_shares(), _cfg.max_shares.get(), [this] () -> float {
         _last_backlog = backlog();
         auto b = _last_backlog / available_memory();
         // This means we are using an unimplemented strategy
@@ -1033,6 +1033,10 @@ compaction_manager::compaction_manager(config cfg, abort_source& as, tasks::task
     , _throughput_updater(serialized_action([this] { return update_throughput(throughput_mbs()); }))
     , _update_compaction_static_shares_action([this] { return update_static_shares(static_shares()); })
     , _compaction_static_shares_observer(_cfg.static_shares.observe(_update_compaction_static_shares_action.make_observer()))
+    , _compaction_max_shares_observer(_cfg.max_shares.observe([this] (const float& max_shares) {
+        cmlog.info("Updating max shares to {}", max_shares);
+        _compaction_controller.set_max_shares(max_shares);
+    }))
     , _strategy_control(std::make_unique<strategy_control>(*this))
     , _tombstone_gc_state(_shared_tombstone_gc_state) {
     tm.register_module(_task_manager_module->get_name(), _task_manager_module);
@@ -1051,11 +1055,12 @@ compaction_manager::compaction_manager(tasks::task_manager& tm)
     , _sys_ks("compaction_manager::system_keyspace")
     , _cfg(config{ .available_memory = 1 })
     , _compaction_submission_timer(compaction_sg(), compaction_submission_callback())
-    , _compaction_controller(make_compaction_controller(compaction_sg(), 1, [] () -> float { return 1.0; }))
+    , _compaction_controller(make_compaction_controller(compaction_sg(), 1, std::nullopt, [] () -> float { return 1.0; }))
     , _backlog_manager(_compaction_controller)
     , _throughput_updater(serialized_action([this] { return update_throughput(throughput_mbs()); }))
     , _update_compaction_static_shares_action([] { return make_ready_future<>(); })
     , _compaction_static_shares_observer(_cfg.static_shares.observe(_update_compaction_static_shares_action.make_observer()))
+    , _compaction_max_shares_observer(_cfg.max_shares.observe([] (const float& max_shares) {}))
     , _strategy_control(std::make_unique<strategy_control>(*this))
     , _tombstone_gc_state(_shared_tombstone_gc_state) {
     tm.register_module(_task_manager_module->get_name(), _task_manager_module);

compaction/compaction_manager.hh

@@ -80,6 +80,7 @@ public:
         scheduling_group maintenance_sched_group;
         size_t available_memory = 0;
         utils::updateable_value<float> static_shares = utils::updateable_value<float>(0);
+        utils::updateable_value<float> max_shares = utils::updateable_value<float>(0);
         utils::updateable_value<uint32_t> throughput_mb_per_sec = utils::updateable_value<uint32_t>(0);
         std::chrono::seconds flush_all_tables_before_major = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::days(1));
     };
@@ -159,6 +160,7 @@ private:
     std::optional<utils::observer<uint32_t>> _throughput_option_observer;
     serialized_action _update_compaction_static_shares_action;
     utils::observer<float> _compaction_static_shares_observer;
+    utils::observer<float> _compaction_max_shares_observer;
     uint64_t _validation_errors = 0;
 
     class strategy_control;
@@ -291,6 +293,10 @@ public:
         return _cfg.static_shares.get();
     }
 
+    float max_shares() const noexcept {
+        return _cfg.max_shares.get();
+    }
+
     uint32_t throughput_mbs() const noexcept {
         return _cfg.throughput_mb_per_sec.get();
     }

compaction/task_manager_module.cc

@@ -227,7 +227,7 @@ future<> run_table_tasks(replica::database& db, std::vector<table_tasks_info> ta
                 // Tables will be kept in descending order.
                 std::ranges::sort(table_tasks, std::greater<>(), [&] (const table_tasks_info& tti) {
                     try {
-                        return db.find_column_family(tti.ti.id).get_stats().live_disk_space_used;
+                        return db.find_column_family(tti.ti.id).get_stats().live_disk_space_used.on_disk;
                     } catch (const replica::no_such_column_family& e) {
                         return int64_t(-1);
                     }
@@ -281,7 +281,7 @@ future<> run_keyspace_tasks(replica::database& db, std::vector<keyspace_tasks_in
                     try {
                         return std::accumulate(kti.table_infos.begin(), kti.table_infos.end(), int64_t(0), [&] (int64_t sum, const table_info& t) {
                             try {
-                                sum += db.find_column_family(t.id).get_stats().live_disk_space_used;
+                                sum += db.find_column_family(t.id).get_stats().live_disk_space_used.on_disk;
                             } catch (const replica::no_such_column_family&) {
                                 // ignore
                             }

conf/scylla.yaml

@@ -888,9 +888,18 @@ rf_rack_valid_keyspaces: false
 #
 # Vector Store options
 #
-# A comma-separated list of URIs for the vector store using DNS name. Only HTTP schema is supported. Port number is mandatory.
+# HTTP and HTTPS schemes are supported. Port number is mandatory.
-# Default is empty, which means that the vector store is not used.
+# If both `vector_store_primary_uri` and `vector_store_secondary_uri` are unset or empty, vector search is disabled.
+#
+# A comma-separated list of primary vector store node URIs. These nodes are preferred for vector search operations.
 # vector_store_primary_uri: http://vector-store.dns.name:{port}
+#
+# A comma-separated list of secondary vector store node URIs. These nodes are used as a fallback when all primary nodes are unavailable, and are typically located in a different availability zone for high availability.
+# vector_store_secondary_uri: http://vector-store.dns.name:{port}
+#
+# Options for encrypted connections to the vector store. These options are used for HTTPS URIs in vector_store_primary_uri and vector_store_secondary_uri.
+# vector_store_encryption_options:
+#    truststore: <not set, use system trust>
 
 # 
 # io-streaming rate limiting

configure.py

@@ -445,6 +445,7 @@ ldap_tests = set([
 scylla_tests = set([
     'test/boost/combined_tests',
     'test/boost/UUID_test',
+    'test/boost/url_parse_test',
     'test/boost/advanced_rpc_compressor_test',
     'test/boost/allocation_strategy_test',
     'test/boost/alternator_unit_test',
@@ -646,6 +647,28 @@ vector_search_tests = set([
     'test/vector_search/client_test'
 ])
 
+vector_search_validator_bin = 'vector-search-validator/bin/vector-search-validator'
+vector_search_validator_deps = set([
+    'test/vector_search_validator/build-validator',
+    'test/vector_search_validator/Cargo.toml',
+    'test/vector_search_validator/crates/validator/Cargo.toml',
+    'test/vector_search_validator/crates/validator/src/main.rs',
+    'test/vector_search_validator/crates/validator-scylla/Cargo.toml',
+    'test/vector_search_validator/crates/validator-scylla/src/lib.rs',
+    'test/vector_search_validator/crates/validator-scylla/src/cql.rs',
+])
+
+vector_store_bin = 'vector-search-validator/bin/vector-store'
+vector_store_deps = set([
+    'test/vector_search_validator/build-env',
+    'test/vector_search_validator/build-vector-store',
+])
+
+vector_search_validator_bins = set([
+    vector_search_validator_bin,
+    vector_store_bin,
+])
+
 wasms = set([
     'wasm/return_input.wat',
     'wasm/test_complex_null_values.wat',
@@ -679,7 +702,7 @@ other = set([
     'iotune',
 ])
 
-all_artifacts = apps | cpp_apps | tests | other | wasms
+all_artifacts = apps | cpp_apps | tests | other | wasms | vector_search_validator_bins
 
 arg_parser = argparse.ArgumentParser('Configure scylla', add_help=False, formatter_class=argparse.ArgumentDefaultsHelpFormatter)
 arg_parser.add_argument('--out', dest='buildfile', action='store', default='build.ninja',
@@ -763,6 +786,7 @@ arg_parser.add_argument('--use-cmake', action=argparse.BooleanOptionalAction, de
 arg_parser.add_argument('--coverage', action = 'store_true', help = 'Compile scylla with coverage instrumentation')
 arg_parser.add_argument('--build-dir', action='store', default='build',
                         help='Build directory path')
+arg_parser.add_argument('--disable-precompiled-header', action='store_true', default=False, help='Disable precompiled header for scylla binary')
 arg_parser.add_argument('-h', '--help', action='store_true', help='show this help message and exit')
 args = arg_parser.parse_args()
 if args.help:
@@ -1172,6 +1196,7 @@ scylla_core = (['message/messaging_service.cc',
                 'auth/allow_all_authorizer.cc',
                 'auth/authenticated_user.cc',
                 'auth/authenticator.cc',
+                'auth/cache.cc',
                 'auth/common.cc',
                 'auth/default_authorizer.cc',
                 'auth/resource.cc',
@@ -1268,7 +1293,8 @@ scylla_core = (['message/messaging_service.cc',
                 'vector_search/vector_store_client.cc',
                 'vector_search/dns.cc',
                 'vector_search/client.cc',
-                'vector_search/clients.cc'
+                'vector_search/clients.cc',
+                'vector_search/truststore.cc'
                 ] + [Antlr3Grammar('cql3/Cql.g')] \
                   + scylla_raft_core
                )
@@ -1579,6 +1605,7 @@ deps['test/boost/combined_tests'] += [
     'test/boost/query_processor_test.cc',
     'test/boost/reader_concurrency_semaphore_test.cc',
     'test/boost/repair_test.cc',
+    'test/boost/replicator_test.cc',
     'test/boost/restrictions_test.cc',
     'test/boost/role_manager_test.cc',
     'test/boost/row_cache_test.cc',
@@ -1621,6 +1648,7 @@ deps['test/boost/bytes_ostream_test'] = [
 ]
 deps['test/boost/input_stream_test'] = ['test/boost/input_stream_test.cc']
 deps['test/boost/UUID_test'] = ['clocks-impl.cc', 'utils/UUID_gen.cc', 'test/boost/UUID_test.cc', 'utils/uuid.cc', 'utils/dynamic_bitset.cc', 'utils/hashers.cc', 'utils/on_internal_error.cc']
+deps['test/boost/url_parse_test'] = ['utils/http.cc', 'test/boost/url_parse_test.cc', ]
 deps['test/boost/murmur_hash_test'] = ['bytes.cc', 'utils/murmur_hash.cc', 'test/boost/murmur_hash_test.cc']
 deps['test/boost/allocation_strategy_test'] = ['test/boost/allocation_strategy_test.cc', 'utils/logalloc.cc', 'utils/dynamic_bitset.cc', 'utils/labels.cc']
 deps['test/boost/log_heap_test'] = ['test/boost/log_heap_test.cc']
@@ -2185,7 +2213,15 @@ if os.path.exists(kmipc_lib):
     user_cflags += f' -I{kmipc_dir}/include -DHAVE_KMIP'
 
 def get_extra_cxxflags(mode, mode_config, cxx, debuginfo):
-    cxxflags = []
+    cxxflags = [
+        # we need this flag for correct precompiled header handling in connection with ccache (or similar)
+        # `git` tools don't preserve timestamps, so when using ccache it might be possible to add pch to ccache
+        # and then later (after for example rebase) get `stdafx.hh` with different timestamp, but the same content.
+        # this will tell ccache to bring pch from its cache. Later on clang will check if timestamps match and complain.
+        # Adding `-fpch-validate-input-files-content` tells clang to check content of stdafx.hh if timestamps don't match.
+        # The flag seems to be present in gcc as well.
+        "" if args.disable_precompiled_header else '-fpch-validate-input-files-content'
+    ]
 
     optimization_level = mode_config['optimization-level']
     cxxflags.append(f'-O{optimization_level}')
@@ -2250,6 +2286,7 @@ def write_build_file(f,
                      scylla_version,
                      scylla_release,
                      args):
+    use_precompiled_header = not args.disable_precompiled_header
     warnings = get_warning_options(args.cxx)
     rustc_target = pick_rustc_target('wasm32-wasi', 'wasm32-wasip1')
     f.write(textwrap.dedent('''\
@@ -2356,7 +2393,10 @@ def write_build_file(f,
 
     for mode in build_modes:
         modeval = modes[mode]
-
+        seastar_lib_ext = 'so' if modeval['build_seastar_shared_libs'] else 'a'
+        seastar_dep = f'$builddir/{mode}/seastar/libseastar.{seastar_lib_ext}'
+        seastar_testing_dep = f'$builddir/{mode}/seastar/libseastar_testing.{seastar_lib_ext}'
+        abseil_dep = ' '.join(f'$builddir/{mode}/abseil/{lib}' for lib in abseil_libs)
         fmt_lib = 'fmt'
         f.write(textwrap.dedent('''\
             cxx_ld_flags_{mode} = {cxx_ld_flags}
@@ -2369,6 +2409,14 @@ def write_build_file(f,
               command = $cxx -MD -MT $out -MF $out.d {seastar_cflags} $cxxflags_{mode} $cxxflags $obj_cxxflags -c -o $out $in
               description = CXX $out
               depfile = $out.d
+            rule cxx_build_precompiled_header.{mode}
+              command = $cxx -MD -MT $out -MF $out.d {seastar_cflags} $cxxflags_{mode} $cxxflags $obj_cxxflags -c -o $out $in -Winvalid-pch -fpch-instantiate-templates -Xclang -emit-pch -DSCYLLA_USE_PRECOMPILED_HEADER
+              description = CXX-PRECOMPILED-HEADER $out
+              depfile = $out.d
+            rule cxx_with_pch.{mode}
+              command = $cxx -MD -MT $out -MF $out.d {seastar_cflags} $cxxflags_{mode} $cxxflags $obj_cxxflags -c -o $out $in -Winvalid-pch -Xclang -include-pch -Xclang $builddir/{mode}/stdafx.hh.pch
+              description = CXX $out
+              depfile = $out.d
             rule link.{mode}
               command = $cxx  $ld_flags_{mode} $ldflags -o $out $in $libs $libs_{mode}
               description = LINK $out
@@ -2402,7 +2450,7 @@ def write_build_file(f,
                         $builddir/{mode}/gen/${{stem}}Parser.cpp
                 description = ANTLR3 $in
             rule checkhh.{mode}
-              command = $cxx -MD -MT $out -MF $out.d {seastar_cflags} $cxxflags $cxxflags_{mode} $obj_cxxflags --include $in -c -o $out $builddir/{mode}/gen/empty.cc
+              command = $cxx -MD -MT $out -MF $out.d {seastar_cflags} $cxxflags $cxxflags_{mode} $obj_cxxflags --include $in -c -o $out $builddir/{mode}/gen/empty.cc -USCYLLA_USE_PRECOMPILED_HEADER
               description = CHECKHH $in
               depfile = $out.d
             rule test.{mode}
@@ -2416,10 +2464,11 @@ def write_build_file(f,
               description = RUST_LIB $out
             ''').format(mode=mode, antlr3_exec=args.antlr3_exec, fmt_lib=fmt_lib, test_repeat=args.test_repeat, test_timeout=args.test_timeout, **modeval))
         f.write(
-            'build {mode}-build: phony {artifacts} {wasms}\n'.format(
+            'build {mode}-build: phony {artifacts} {wasms} {vector_search_validator_bins}\n'.format(
                 mode=mode,
-                artifacts=str.join(' ', ['$builddir/' + mode + '/' + x for x in sorted(build_artifacts - wasms)]),
+                artifacts=str.join(' ', ['$builddir/' + mode + '/' + x for x in sorted(build_artifacts - wasms - vector_search_validator_bins)]),
                 wasms = str.join(' ', ['$builddir/' + x for x in sorted(build_artifacts & wasms)]),
+                vector_search_validator_bins=str.join(' ', ['$builddir/' + x for x in sorted(build_artifacts & vector_search_validator_bins)]),
             )
         )
         if profile_recipe := modes[mode].get('profile_recipe'):
@@ -2428,6 +2477,7 @@ def write_build_file(f,
         include_dist_target = f'dist-{mode}' if args.enable_dist is None or args.enable_dist else ''
         f.write(f'build {mode}: phony {include_cxx_target} {include_dist_target}\n')
         compiles = {}
+        compiles_with_pch = set()
         swaggers = set()
         serializers = {}
         ragels = {}
@@ -2442,16 +2492,16 @@ def write_build_file(f,
         # object code. And we enable LTO when linking the main Scylla executable, while disable
         # it when linking anything else.
 
-        seastar_lib_ext = 'so' if modeval['build_seastar_shared_libs'] else 'a'
         for binary in sorted(build_artifacts):
             if modeval['is_profile'] and binary != "scylla":
                 # Just to avoid clutter in build.ninja
                 continue
             profile_dep = modes[mode].get('profile_target', "")
 
-            if binary in other or binary in wasms:
+            if binary in other or binary in wasms or binary in vector_search_validator_bins:
                 continue
             srcs = deps[binary]
+            # 'scylla'
             objs = ['$builddir/' + mode + '/' + src.replace('.cc', '.o')
                     for src in srcs
                     if src.endswith('.cc')]
@@ -2487,9 +2537,6 @@ def write_build_file(f,
                 continue
 
             do_lto = modes[mode]['has_lto'] and binary in lto_binaries
-            seastar_dep = f'$builddir/{mode}/seastar/libseastar.{seastar_lib_ext}'
-            seastar_testing_dep = f'$builddir/{mode}/seastar/libseastar_testing.{seastar_lib_ext}'
-            abseil_dep = ' '.join(f'$builddir/{mode}/abseil/{lib}' for lib in abseil_libs)
             seastar_testing_libs = f'$seastar_testing_libs_{mode}'
 
             local_libs = f'$seastar_libs_{mode} $libs'
@@ -2499,6 +2546,7 @@ def write_build_file(f,
                 local_libs += ' -flto=thin -ffat-lto-objects'
             else:
                 local_libs += ' -fno-lto'
+            use_pch = use_precompiled_header and binary == 'scylla'
             if binary in tests:
                 if binary in pure_boost_tests:
                     local_libs += ' ' + maybe_static(args.staticboost, '-lboost_unit_test_framework')
@@ -2527,6 +2575,8 @@ def write_build_file(f,
                 if src.endswith('.cc'):
                     obj = '$builddir/' + mode + '/' + src.replace('.cc', '.o')
                     compiles[obj] = src
+                    if use_pch:
+                        compiles_with_pch.add(obj)
                 elif src.endswith('.idl.hh'):
                     hh = '$builddir/' + mode + '/gen/' + src.replace('.idl.hh', '.dist.hh')
                     serializers[hh] = src
@@ -2559,10 +2609,11 @@ def write_build_file(f,
         )
 
         f.write(
-            'build {mode}-test: test.{mode} {test_executables} $builddir/{mode}/scylla {wasms}\n'.format(
+            'build {mode}-test: test.{mode} {test_executables} $builddir/{mode}/scylla {wasms} {vector_search_validator_bins} \n'.format(
                 mode=mode,
                 test_executables=' '.join(['$builddir/{}/{}'.format(mode, binary) for binary in sorted(tests)]),
                 wasms=' '.join([f'$builddir/{binary}' for binary in sorted(wasms)]),
+                vector_search_validator_bins=' '.join([f'$builddir/{binary}' for binary in sorted(vector_search_validator_bins)]),
             )
         )
         f.write(
@@ -2605,7 +2656,9 @@ def write_build_file(f,
             src = compiles[obj]
             seastar_dep = f'$builddir/{mode}/seastar/libseastar.{seastar_lib_ext}'
             abseil_dep = ' '.join(f'$builddir/{mode}/abseil/{lib}' for lib in abseil_libs)
-            f.write(f'build {obj}: cxx.{mode} {src} | {profile_dep} || {seastar_dep} {abseil_dep} {gen_headers_dep}\n')
+            pch_dep = f'$builddir/{mode}/stdafx.hh.pch' if obj in compiles_with_pch else ''
+            cxx_cmd = 'cxx_with_pch' if obj in compiles_with_pch else 'cxx'
+            f.write(f'build {obj}: {cxx_cmd}.{mode} {src} | {profile_dep} {seastar_dep} {abseil_dep} {gen_headers_dep} {pch_dep}\n')
             if src in modeval['per_src_extra_cxxflags']:
                 f.write('    cxxflags = {seastar_cflags} $cxxflags $cxxflags_{mode} {extra_cxxflags}\n'.format(mode=mode, extra_cxxflags=modeval["per_src_extra_cxxflags"][src], **modeval))
         for swagger in swaggers:
@@ -2666,6 +2719,8 @@ def write_build_file(f,
             f.write('  target = {lib}\n'.format(**locals()))
             f.write('  profile_dep = {profile_dep}\n'.format(**locals()))
 
+        f.write(f'build $builddir/{mode}/stdafx.hh.pch: cxx_build_precompiled_header.{mode} stdafx.hh | {profile_dep} {seastar_dep} {abseil_dep} {gen_headers_dep} {pch_dep}\n')
+
         f.write('build $builddir/{mode}/seastar/apps/iotune/iotune: ninja $builddir/{mode}/seastar/build.ninja | $builddir/{mode}/seastar/libseastar.{seastar_lib_ext}\n'
                 .format(**locals()))
         f.write('  pool = submodule_pool\n')
@@ -2729,6 +2784,19 @@ def write_build_file(f,
             'build compiler-training: phony {}\n'.format(' '.join(['{mode}-compiler-training'.format(mode=mode) for mode in default_modes]))
     )
 
+    f.write(textwrap.dedent(f'''\
+        rule build-vector-search-validator
+            command = test/vector_search_validator/build-validator $builddir
+        rule build-vector-store
+            command = test/vector_search_validator/build-vector-store $builddir
+        '''))
+    f.write(
+            'build $builddir/{vector_search_validator_bin}: build-vector-search-validator {}\n'.format(' '.join([dep for dep in sorted(vector_search_validator_deps)]), vector_search_validator_bin=vector_search_validator_bin)
+    )
+    f.write(
+            'build $builddir/{vector_store_bin}: build-vector-store {}\n'.format(' '.join([dep for dep in sorted(vector_store_deps)]), vector_store_bin=vector_store_bin)
+    )
+
     f.write(textwrap.dedent(f'''\
         build dist-unified-tar: phony {' '.join([f'$builddir/{mode}/dist/tar/{scylla_product}-unified-{scylla_version}-{scylla_release}.{arch}.tar.gz' for mode in default_modes])}
         build dist-unified: phony dist-unified-tar
@@ -2942,7 +3010,7 @@ def configure_using_cmake(args):
         'CMAKE_DEFAULT_CONFIGS': selected_configs,
         'CMAKE_C_COMPILER': args.cc,
         'CMAKE_CXX_COMPILER': args.cxx,
-        'CMAKE_CXX_FLAGS': args.user_cflags,
+        'CMAKE_CXX_FLAGS': args.user_cflags + ("" if args.disable_precompiled_header else " -fpch-validate-input-files-content"),
         'CMAKE_EXE_LINKER_FLAGS': args.user_ldflags,
         'CMAKE_EXPORT_COMPILE_COMMANDS': 'ON',
         'Scylla_CHECK_HEADERS': 'ON',
@@ -2951,6 +3019,7 @@ def configure_using_cmake(args):
         'Scylla_TEST_REPEAT': args.test_repeat,
         'Scylla_ENABLE_LTO': 'ON' if args.lto else 'OFF',
         'Scylla_WITH_DEBUG_INFO' : 'ON' if args.debuginfo else 'OFF',
+        'Scylla_USE_PRECOMPILED_HEADER': 'OFF' if args.disable_precompiled_header else 'ON',
     }
     if args.date_stamp:
         settings['Scylla_DATE_STAMP'] = args.date_stamp

cql3/CMakeLists.txt

@@ -138,5 +138,8 @@ target_link_libraries(cql3
     lang
     transport)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(cql3 REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers cql3
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

cql3/Cql.g

@@ -575,6 +575,15 @@ usingTimeoutServiceLevelClauseObjective[std::unique_ptr<cql3::attributes::raw>&
     | serviceLevel sl_name=serviceLevelOrRoleName { attrs->service_level = std::move(sl_name); }
     ;
 
+usingTimeoutConcurrencyClause[std::unique_ptr<cql3::attributes::raw>& attrs]
+    : K_USING usingTimeoutConcurrencyClauseObjective[attrs] ( K_AND usingTimeoutConcurrencyClauseObjective[attrs] )*
+    ;
+
+usingTimeoutConcurrencyClauseObjective[std::unique_ptr<cql3::attributes::raw>& attrs]
+    : K_TIMEOUT to=term { attrs->timeout = std::move(to); }
+    | K_CONCURRENCY c=term { attrs->concurrency = std::move(c); }
+    ;
+
 /**
  * UPDATE <CF>
  * USING TIMESTAMP <long>
@@ -666,7 +675,7 @@ pruneMaterializedViewStatement returns [std::unique_ptr<raw::select_statement> e
         auto attrs = std::make_unique<cql3::attributes::raw>();
         expression wclause = conjunction{};
     }
-	: K_PRUNE K_MATERIALIZED K_VIEW cf=columnFamilyName (K_WHERE w=whereClause { wclause = std::move(w); } )? ( usingClause[attrs] )?
+	: K_PRUNE K_MATERIALIZED K_VIEW cf=columnFamilyName (K_WHERE w=whereClause { wclause = std::move(w); } )? ( usingTimeoutConcurrencyClause[attrs] )?
 	  {
 	        auto params = make_lw_shared<raw::select_statement::parameters>(std::move(orderings), is_distinct, allow_filtering, statement_subtype, bypass_cache);
 	        return std::make_unique<raw::select_statement>(std::move(cf), std::move(params),
@@ -1560,6 +1569,10 @@ serviceLevelOrRoleName returns [sstring name]
 | t=QUOTED_NAME        { $name = sstring($t.text); }
 | k=unreserved_keyword { $name = k;
 						 std::transform($name.begin(), $name.end(), $name.begin(), ::tolower);}
+// The literal `default` will not be parsed by any of the previous
+// rules, so we need to cover it manually. Needed by CREATE SERVICE
+// LEVEL and ATTACH SERVICE LEVEL.
+| t=K_DEFAULT          { $name = sstring("default"); }
 | QMARK {add_recognition_error("Bind variables cannot be used for service levels or role names");}
 ;
 
@@ -2366,6 +2379,7 @@ K_LIKE:        L I K E;
 
 K_TIMEOUT:     T I M E O U T;
 K_PRUNE:       P R U N E;
+K_CONCURRENCY: C O N C U R R E N C Y;
 
 K_EXECUTE:     E X E C U T E;
 

cql3/attributes.cc

@@ -20,19 +20,21 @@
 namespace cql3 {
 
 std::unique_ptr<attributes> attributes::none() {
-    return std::unique_ptr<attributes>{new attributes{{}, {}, {}, {}}};
+    return std::unique_ptr<attributes>{new attributes{{}, {}, {}, {}, {}}};
 }
 
 attributes::attributes(std::optional<cql3::expr::expression>&& timestamp,
                        std::optional<cql3::expr::expression>&& time_to_live,
                        std::optional<cql3::expr::expression>&& timeout,
-                       std::optional<sstring> service_level)
+                       std::optional<sstring> service_level,
+                       std::optional<cql3::expr::expression>&& concurrency)
     : _timestamp_unset_guard(timestamp)
     , _timestamp{std::move(timestamp)}
     , _time_to_live_unset_guard(time_to_live)
     , _time_to_live{std::move(time_to_live)}
     , _timeout{std::move(timeout)}
     , _service_level(std::move(service_level))
+    , _concurrency{std::move(concurrency)}
 { }
 
 bool attributes::is_timestamp_set() const {
@@ -51,6 +53,10 @@ bool attributes::is_service_level_set() const {
     return bool(_service_level);
 }
 
+bool attributes::is_concurrency_set() const {
+    return bool(_concurrency);
+}
+
 int64_t attributes::get_timestamp(int64_t now, const query_options& options) {
     if (!_timestamp.has_value() || _timestamp_unset_guard.is_unset(options)) {
         return now;
@@ -123,6 +129,27 @@ qos::service_level_options attributes::get_service_level(qos::service_level_cont
     return sl_controller.get_service_level(sl_name).slo;
 }
 
+std::optional<int32_t> attributes::get_concurrency(const query_options& options) const {
+    if (!_concurrency.has_value()) {
+        return std::nullopt;
+    }
+
+    cql3::raw_value concurrency_raw = expr::evaluate(*_concurrency, options);
+    if (concurrency_raw.is_null()) {
+        throw exceptions::invalid_request_exception("Invalid null value of concurrency");
+    }
+    int32_t concurrency;
+    try {
+        concurrency = concurrency_raw.view().validate_and_deserialize<int32_t>(*int32_type);
+    } catch (marshal_exception& e) {
+        throw exceptions::invalid_request_exception("Invalid concurrency value");
+    }
+    if (concurrency <= 0) {
+        throw exceptions::invalid_request_exception("Concurrency must be a positive integer");
+    }
+    return concurrency;
+}
+
 void attributes::fill_prepare_context(prepare_context& ctx) {
     if (_timestamp.has_value()) {
         expr::fill_prepare_context(*_timestamp, ctx);
@@ -133,10 +160,13 @@ void attributes::fill_prepare_context(prepare_context& ctx) {
     if (_timeout.has_value()) {
         expr::fill_prepare_context(*_timeout, ctx);
     }
+    if (_concurrency.has_value()) {
+        expr::fill_prepare_context(*_concurrency, ctx);
+    }
 }
 
 std::unique_ptr<attributes> attributes::raw::prepare(data_dictionary::database db, const sstring& ks_name, const sstring& cf_name) const {
-    std::optional<expr::expression> ts, ttl, to;
+    std::optional<expr::expression> ts, ttl, to, conc;
 
     if (timestamp.has_value()) {
         ts = prepare_expression(*timestamp, db, ks_name, nullptr, timestamp_receiver(ks_name, cf_name));
@@ -153,7 +183,12 @@ std::unique_ptr<attributes> attributes::raw::prepare(data_dictionary::database d
         verify_no_aggregate_functions(*timeout, "USING clause");
     }
 
-    return std::unique_ptr<attributes>{new attributes{std::move(ts), std::move(ttl), std::move(to), std::move(service_level)}};
+    if (concurrency.has_value()) {
+        conc = prepare_expression(*concurrency, db, ks_name, nullptr, concurrency_receiver(ks_name, cf_name));
+        verify_no_aggregate_functions(*concurrency, "USING clause");
+    }
+
+    return std::unique_ptr<attributes>{new attributes{std::move(ts), std::move(ttl), std::move(to), std::move(service_level), std::move(conc)}};
 }
 
 lw_shared_ptr<column_specification> attributes::raw::timestamp_receiver(const sstring& ks_name, const sstring& cf_name) const {
@@ -168,4 +203,8 @@ lw_shared_ptr<column_specification> attributes::raw::timeout_receiver(const sstr
     return make_lw_shared<column_specification>(ks_name, cf_name, ::make_shared<column_identifier>("[timeout]", true), duration_type);
 }
 
+lw_shared_ptr<column_specification> attributes::raw::concurrency_receiver(const sstring& ks_name, const sstring& cf_name) const {
+    return make_lw_shared<column_specification>(ks_name, cf_name, ::make_shared<column_identifier>("[concurrency]", true), data_type_for<int32_t>());
+}
+
 }

cql3/attributes.hh

@@ -36,13 +36,15 @@ private:
     std::optional<cql3::expr::expression> _time_to_live;
     std::optional<cql3::expr::expression> _timeout;
     std::optional<sstring> _service_level;
+    std::optional<cql3::expr::expression> _concurrency;
 public:
     static std::unique_ptr<attributes> none();
 private:
     attributes(std::optional<cql3::expr::expression>&& timestamp,
                std::optional<cql3::expr::expression>&& time_to_live,
                std::optional<cql3::expr::expression>&& timeout,
-               std::optional<sstring> service_level);
+               std::optional<sstring> service_level,
+               std::optional<cql3::expr::expression>&& concurrency);
 public:
     bool is_timestamp_set() const;
 
@@ -52,6 +54,8 @@ public:
 
     bool is_service_level_set() const;
 
+    bool is_concurrency_set() const;
+
     int64_t get_timestamp(int64_t now, const query_options& options);
 
     std::optional<int32_t> get_time_to_live(const query_options& options);
@@ -60,6 +64,8 @@ public:
 
     qos::service_level_options get_service_level(qos::service_level_controller& sl_controller) const;
 
+    std::optional<int32_t> get_concurrency(const query_options& options) const;
+
     void fill_prepare_context(prepare_context& ctx);
 
     class raw final {
@@ -68,6 +74,7 @@ public:
         std::optional<cql3::expr::expression> time_to_live;
         std::optional<cql3::expr::expression> timeout;
         std::optional<sstring> service_level;
+        std::optional<cql3::expr::expression> concurrency;
 
         std::unique_ptr<attributes> prepare(data_dictionary::database db, const sstring& ks_name, const sstring& cf_name) const;
     private:
@@ -76,6 +83,8 @@ public:
         lw_shared_ptr<column_specification> time_to_live_receiver(const sstring& ks_name, const sstring& cf_name) const;
 
         lw_shared_ptr<column_specification> timeout_receiver(const sstring& ks_name, const sstring& cf_name) const;
+
+        lw_shared_ptr<column_specification> concurrency_receiver(const sstring& ks_name, const sstring& cf_name) const;
     };
 };
 

cql3/statements/alter_service_level_statement.cc

@@ -37,6 +37,12 @@ future<::shared_ptr<cql_transport::messages::result_message>>
 alter_service_level_statement::execute(query_processor& qp,
         service::query_state &state,
         const query_options &, std::optional<service::group0_guard> guard) const {
+    if (_service_level == qos::service_level_controller::default_service_level_name) {
+        sstring reason = seastar::format("The default service level, {}, cannot be altered",
+                qos::service_level_controller::default_service_level_name);
+        throw exceptions::invalid_request_exception(std::move(reason));
+    }
+
     service::group0_batch mc{std::move(guard)};
     validate_shares_option(qp, _slo);
     qos::service_level& sl = state.get_service_level_controller().get_service_level(_service_level);

cql3/statements/alter_table_statement.cc

@@ -186,10 +186,6 @@ void alter_table_statement::add_column(const query_options&, const schema& schem
         if (!schema.is_compound()) {
             throw exceptions::invalid_request_exception("Cannot use non-frozen collections with a non-composite PRIMARY KEY");
         }
-        if (schema.is_super()) {
-            throw exceptions::invalid_request_exception("Cannot use non-frozen collections with super column families");
-        }
-
 
         // If there used to be a non-frozen collection column with the same name (that has been dropped),
         // we could still have some data using the old type, and so we can't allow adding a collection
@@ -422,7 +418,14 @@ std::pair<schema_ptr, std::vector<view_ptr>> alter_table_statement::prepare_sche
                 throw exceptions::invalid_request_exception(format("The synchronous_updates option is only applicable to materialized views, not to base tables"));
             }
 
-            _properties->apply_to_builder(cfm, std::move(schema_extensions), db, keyspace());
+            if (is_cdc_log_table) {
+                auto gc_opts = _properties->get_tombstone_gc_options(schema_extensions);
+                if (gc_opts && gc_opts->mode() == tombstone_gc_mode::repair) {
+                    throw exceptions::invalid_request_exception("The 'repair' mode for tombstone_gc is not allowed on CDC log tables.");
+                }
+            }
+
+            _properties->apply_to_builder(cfm, std::move(schema_extensions), db, keyspace(), !is_cdc_log_table);
         }
         break;
 

cql3/statements/alter_view_statement.cc

@@ -55,8 +55,29 @@ view_ptr alter_view_statement::prepare_view(data_dictionary::database db) const
     auto schema_extensions = _properties->make_schema_extensions(db.extensions());
     _properties->validate(db, keyspace(), schema_extensions);
 
+    bool is_colocated = [&] {
+        if (!db.find_keyspace(keyspace()).get_replication_strategy().uses_tablets()) {
+            return false;
+        }
+        auto base_schema = db.find_schema(schema->view_info()->base_id());
+        if (!base_schema) {
+            return false;
+        }
+        return std::ranges::equal(
+            schema->partition_key_columns(),
+            base_schema->partition_key_columns(),
+            [](const column_definition& a, const column_definition& b) { return a.name() == b.name(); });
+    }();
+
+    if (is_colocated) {
+        auto gc_opts = _properties->get_tombstone_gc_options(schema_extensions);
+        if (gc_opts && gc_opts->mode() == tombstone_gc_mode::repair) {
+            throw exceptions::invalid_request_exception("The 'repair' mode for tombstone_gc is not allowed on co-located materialized view tables.");
+        }
+    }
+
     auto builder = schema_builder(schema);
-    _properties->apply_to_builder(builder, std::move(schema_extensions), db, keyspace());
+    _properties->apply_to_builder(builder, std::move(schema_extensions), db, keyspace(), !is_colocated);
 
     if (builder.get_gc_grace_seconds() == 0) {
         throw exceptions::invalid_request_exception(

cql3/statements/attach_service_level_statement.cc

@@ -43,6 +43,14 @@ attach_service_level_statement::execute(query_processor& qp,
         service::query_state &state,
         const query_options &,
         std::optional<service::group0_guard> guard) const {
+    if (_service_level == qos::service_level_controller::default_service_level_name) {
+        sstring reason = seastar::format("The default service level, {}, cannot be "
+                "attached to a role. If you want to detach an attached service level, "
+                "use the DETACH SERVICE LEVEL statement",
+                qos::service_level_controller::default_service_level_name);
+        throw exceptions::invalid_request_exception(std::move(reason));
+    }
+
     auto sli = co_await state.get_service_level_controller().get_distributed_service_level(_service_level);
     if (sli.empty()) {
         throw qos::nonexistant_service_level_exception(_service_level);

cql3/statements/cf_prop_defs.cc

@@ -293,7 +293,7 @@ std::optional<db::tablet_options::map_type> cf_prop_defs::get_tablet_options() c
     return std::nullopt;
 }
 
-void cf_prop_defs::apply_to_builder(schema_builder& builder, schema::extensions_map schema_extensions, const data_dictionary::database& db, sstring ks_name) const {
+void cf_prop_defs::apply_to_builder(schema_builder& builder, schema::extensions_map schema_extensions, const data_dictionary::database& db, sstring ks_name, bool supports_repair) const {
     if (has_property(KW_COMMENT)) {
         builder.set_comment(get_string(KW_COMMENT, ""));
     }
@@ -379,7 +379,7 @@ void cf_prop_defs::apply_to_builder(schema_builder& builder, schema::extensions_
     }
     // Set default tombstone_gc mode.
     if (!schema_extensions.contains(tombstone_gc_extension::NAME)) {
-        auto ext = seastar::make_shared<tombstone_gc_extension>(get_default_tombstone_gc_mode(db, ks_name));
+        auto ext = seastar::make_shared<tombstone_gc_extension>(get_default_tombstone_gc_mode(db, ks_name, supports_repair));
         schema_extensions.emplace(tombstone_gc_extension::NAME, std::move(ext));
     }
     builder.set_extensions(std::move(schema_extensions));

cql3/statements/cf_prop_defs.hh

@@ -110,7 +110,7 @@ public:
     bool get_synchronous_updates_flag() const;
     std::optional<db::tablet_options::map_type> get_tablet_options() const;
 
-    void apply_to_builder(schema_builder& builder, schema::extensions_map schema_extensions, const data_dictionary::database& db, sstring ks_name) const;
+    void apply_to_builder(schema_builder& builder, schema::extensions_map schema_extensions, const data_dictionary::database& db, sstring ks_name, bool supports_repair) const;
     void validate_minimum_int(const sstring& field, int32_t minimum_value, int32_t default_value) const;
 };
 

cql3/statements/create_index_statement.cc

@@ -201,7 +201,14 @@ view_ptr create_index_statement::create_view_for_index(const schema_ptr schema,
         "";
     builder.with_view_info(schema, false, where_clause);
 
-    auto tombstone_gc_ext = seastar::make_shared<tombstone_gc_extension>(get_default_tombstone_gc_mode(db, schema->ks_name()));
+    bool is_colocated = [&] {
+        if (!db.find_keyspace(keyspace()).get_replication_strategy().uses_tablets()) {
+            return false;
+        }
+        return im.local();
+    }();
+
+    auto tombstone_gc_ext = seastar::make_shared<tombstone_gc_extension>(get_default_tombstone_gc_mode(db, schema->ks_name(), !is_colocated));
     builder.add_extension(tombstone_gc_extension::NAME, std::move(tombstone_gc_ext));
 
     // A local secondary index should be backed by a *synchronous* view,
@@ -272,12 +279,16 @@ std::vector<::shared_ptr<index_target>> create_index_statement::validate_while_e
         throw exceptions::invalid_request_exception(format("index names shouldn't be more than {:d} characters long (got \"{}\")", schema::NAME_LENGTH, _index_name.c_str()));
     }
 
+    // Regular secondary indexes require rf-rack-validity.
+    // Custom indexes need to validate this property themselves, if they need it.
+    if (!_properties || !_properties->custom_class) {
         try {
             db::view::validate_view_keyspace(db, keyspace());
         } catch (const std::exception& e) {
             // The type of the thrown exception is not specified, so we need to wrap it here.
             throw exceptions::invalid_request_exception(e.what());
         }
+    }
 
     validate_for_local_index(*schema);
 
@@ -292,7 +303,7 @@ std::vector<::shared_ptr<index_target>> create_index_statement::validate_while_e
             throw exceptions::invalid_request_exception(format("Non-supported custom class \'{}\' provided", *(_properties->custom_class)));
         }
         auto custom_index = (*custom_index_factory)();
-        custom_index->validate(*schema, *_properties, targets, db.features());
+        custom_index->validate(*schema, *_properties, targets, db.features(), db);
         _properties->index_version = custom_index->index_version(*schema);
     }
 

cql3/statements/create_service_level_statement.cc

@@ -45,6 +45,12 @@ create_service_level_statement::execute(query_processor& qp,
         throw exceptions::invalid_request_exception("Names starting with '$' are reserved for internal tenants. Use a different name.");
     }
 
+    if (_service_level == qos::service_level_controller::default_service_level_name) {
+        sstring reason = seastar::format("The default service level, {}, already exists "
+                "and cannot be created", qos::service_level_controller::default_service_level_name);
+        throw exceptions::invalid_request_exception(std::move(reason));
+    }
+
     service::group0_batch mc{std::move(guard)};
     validate_shares_option(qp, _slo);
     

cql3/statements/create_table_statement.cc

@@ -128,7 +128,7 @@ void create_table_statement::apply_properties_to(schema_builder& builder, const
         builder.set_compressor_params(db.get_config().sstable_compression_user_table_options());
     }
 
-    _properties->apply_to_builder(builder, _properties->make_schema_extensions(db.extensions()), db, keyspace());
+    _properties->apply_to_builder(builder, _properties->make_schema_extensions(db.extensions()), db, keyspace(), true);
 }
 
 void create_table_statement::add_column_metadata_from_aliases(schema_builder& builder, std::vector<bytes> aliases, const std::vector<data_type>& types, column_kind kind) const

cql3/statements/create_view_statement.cc

@@ -373,7 +373,30 @@ std::pair<view_ptr, cql3::cql_warnings_vec> create_view_statement::prepare_view(
             db::view::create_virtual_column(builder, def->name(), def->type);
         }
     }
-    _properties.properties()->apply_to_builder(builder, std::move(schema_extensions), db, keyspace());
+
+    bool is_colocated = [&] {
+        if (!db.find_keyspace(keyspace()).get_replication_strategy().uses_tablets()) {
+            return false;
+        }
+        if (target_partition_keys.size() != schema->partition_key_columns().size()) {
+            return false;
+        }
+        for (size_t i = 0; i < target_partition_keys.size(); ++i) {
+            if (target_partition_keys[i] != &schema->partition_key_columns()[i]) {
+                return false;
+            }
+        }
+        return true;
+    }();
+
+    if (is_colocated) {
+        auto gc_opts = _properties.properties()->get_tombstone_gc_options(schema_extensions);
+        if (gc_opts && gc_opts->mode() == tombstone_gc_mode::repair) {
+            throw exceptions::invalid_request_exception("The 'repair' mode for tombstone_gc is not allowed on co-located materialized view tables.");
+        }
+    }
+
+    _properties.properties()->apply_to_builder(builder, std::move(schema_extensions), db, keyspace(), !is_colocated);
 
     if (builder.default_time_to_live().count() > 0) {
         throw exceptions::invalid_request_exception(

cql3/statements/drop_service_level_statement.cc

@@ -34,6 +34,11 @@ drop_service_level_statement::execute(query_processor& qp,
         service::query_state &state,
         const query_options &,
         std::optional<service::group0_guard> guard) const {
+    if (_service_level == qos::service_level_controller::default_service_level_name) {
+        sstring reason = seastar::format("The default service level, {}, cannot be dropped",
+                qos::service_level_controller::default_service_level_name);
+        throw exceptions::invalid_request_exception(std::move(reason));
+    }
     service::group0_batch mc{std::move(guard)};
     auto& sl = state.get_service_level_controller();
     co_await sl.drop_distributed_service_level(_service_level, _if_exists, mc);

cql3/statements/ks_prop_defs.cc

@@ -8,6 +8,7 @@
  * SPDX-License-Identifier: (LicenseRef-ScyllaDB-Source-Available-1.0 and Apache-2.0)
  */
 
+#include "seastar/core/format.hh"
 #include "seastar/core/sstring.hh"
 #include "utils/assert.hh"
 #include "cql3/statements/ks_prop_defs.hh"
@@ -113,6 +114,17 @@ static locator::replication_strategy_config_options prepare_options(
         return options;
     }
 
+    if (uses_tablets) {
+        for (const auto& opt: old_options) {
+            if (opt.first == ks_prop_defs::REPLICATION_FACTOR_KEY) {
+                on_internal_error(logger, format("prepare_options: old_options contains invalid key '{}'", ks_prop_defs::REPLICATION_FACTOR_KEY));
+            }
+            if (!options.contains(opt.first)) {
+                throw exceptions::configuration_exception(fmt::format("Attempted to implicitly drop replicas in datacenter {}. If this is the desired behavior, set replication factor to 0 in {} explicitly.", opt.first, opt.first));
+            }
+        }
+    }
+
     // For users' convenience, expand the 'replication_factor' option into a replication factor for each DC.
     // If the user simply switches from another strategy without providing any options,
     // but the other strategy used the 'replication_factor' option, it will also be expanded.

cql3/statements/prune_materialized_view_statement.cc

@@ -21,7 +21,7 @@ namespace cql3 {
 namespace statements {
 
 static future<> delete_ghost_rows(dht::partition_range_vector partition_ranges, std::vector<query::clustering_range> clustering_bounds, view_ptr view,
-        service::storage_proxy& proxy, service::query_state& state, const query_options& options, cql_stats& stats, db::timeout_clock::duration timeout_duration) {
+        service::storage_proxy& proxy, service::query_state& state, const query_options& options, cql_stats& stats, db::timeout_clock::duration timeout_duration, size_t concurrency) {
     auto key_columns = std::ranges::to<std::vector<const column_definition*>>(
         view->all_columns()
         | std::views::filter([] (const column_definition& cdef) { return cdef.is_primary_key(); })
@@ -35,7 +35,7 @@ static future<> delete_ghost_rows(dht::partition_range_vector partition_ranges,
     tracing::trace(state.get_trace_state(), "Deleting ghost rows from partition ranges {}", partition_ranges);
 
     auto p = service::pager::query_pagers::ghost_row_deleting_pager(schema_ptr(view), selection, state,
-            options, std::move(command), std::move(partition_ranges), stats, proxy, timeout_duration);
+            options, std::move(command), std::move(partition_ranges), stats, proxy, timeout_duration, concurrency);
 
     int32_t page_size = std::max(options.get_page_size(), 1000);
     auto now = gc_clock::now();
@@ -62,7 +62,8 @@ future<::shared_ptr<cql_transport::messages::result_message>> prune_materialized
     auto timeout_duration = get_timeout(state.get_client_state(), options);
     dht::partition_range_vector key_ranges = _restrictions->get_partition_key_ranges(options);
     std::vector<query::clustering_range> clustering_bounds = _restrictions->get_clustering_bounds(options);
-    return delete_ghost_rows(std::move(key_ranges), std::move(clustering_bounds), view_ptr(_schema), qp.proxy(), state, options, _stats, timeout_duration).then([] {
+    size_t concurrency = _attrs->is_concurrency_set() ? _attrs->get_concurrency(options).value() : 1;
+    return delete_ghost_rows(std::move(key_ranges), std::move(clustering_bounds), view_ptr(_schema), qp.proxy(), state, options, _stats, timeout_duration, concurrency).then([] {
         return make_ready_future<::shared_ptr<cql_transport::messages::result_message>>(::make_shared<cql_transport::messages::result_message::void_message>());
     });
 }

cql3/statements/select_statement.cc

@@ -2031,14 +2031,16 @@ future<shared_ptr<cql_transport::messages::result_message>> vector_indexed_table
                     fmt::format("Use of ANN OF in an ORDER BY clause requires a LIMIT that is not greater than {}. LIMIT was {}", max_ann_query_limit, limit)));
         }
 
-        auto as = abort_source();
+        auto timeout = db::timeout_clock::now() + get_timeout(state.get_client_state(), options);
-        auto pkeys = co_await qp.vector_store_client().ann(_schema->ks_name(), _index.metadata().name(), _schema, get_ann_ordering_vector(options), limit, as);
+        auto aoe = abort_on_expiry(timeout);
+        auto pkeys = co_await qp.vector_store_client().ann(
+                _schema->ks_name(), _index.metadata().name(), _schema, get_ann_ordering_vector(options), limit, aoe.abort_source());
         if (!pkeys.has_value()) {
             co_await coroutine::return_exception(
                     exceptions::invalid_request_exception(std::visit(vector_search::vector_store_client::ann_error_visitor{}, pkeys.error())));
         }
 
-        co_return co_await query_base_table(qp, state, options, pkeys.value());
+        co_return co_await query_base_table(qp, state, options, pkeys.value(), timeout);
     });
 
     auto page_size = options.get_page_size();
@@ -2073,10 +2075,10 @@ std::vector<float> vector_indexed_table_select_statement::get_ann_ordering_vecto
     return util::to_vector<float>(values);
 }
 
-future<::shared_ptr<cql_transport::messages::result_message>> vector_indexed_table_select_statement::query_base_table(
+future<::shared_ptr<cql_transport::messages::result_message>> vector_indexed_table_select_statement::query_base_table(query_processor& qp,
-        query_processor& qp, service::query_state& state, const query_options& options, const std::vector<vector_search::primary_key>& pkeys) const {
+        service::query_state& state, const query_options& options, const std::vector<vector_search::primary_key>& pkeys,
+        lowres_clock::time_point timeout) const {
     auto command = prepare_command_for_base_query(qp, state, options);
-    auto timeout = db::timeout_clock::now() + get_timeout(state.get_client_state(), options);
 
     // For tables without clustering columns, we can optimize by querying
     // partition ranges instead of individual primary keys, since the

cql3/statements/select_statement.hh

@@ -389,8 +389,8 @@ private:
 
     std::vector<float> get_ann_ordering_vector(const query_options& options) const;
 
-    future<::shared_ptr<cql_transport::messages::result_message>> query_base_table(
+    future<::shared_ptr<cql_transport::messages::result_message>> query_base_table(query_processor& qp, service::query_state& state,
-            query_processor& qp, service::query_state& state, const query_options& options, const std::vector<vector_search::primary_key>& pkeys) const;
+            const query_options& options, const std::vector<vector_search::primary_key>& pkeys, lowres_clock::time_point timeout) const;
 
     future<::shared_ptr<cql_transport::messages::result_message>> query_base_table(query_processor& qp, service::query_state& state,
             const query_options& options, lw_shared_ptr<query::read_command> command, lowres_clock::time_point timeout,

data_dictionary/CMakeLists.txt

@@ -12,5 +12,8 @@ target_link_libraries(data_dictionary
     Seastar::seastar
     xxHash::xxhash)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(data_dictionary REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers data_dictionary
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

db/CMakeLists.txt

@@ -60,5 +60,8 @@ target_link_libraries(db
     data_dictionary
     cql3)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(db REUSE_FROM scylla-precompiled-header)
+endif()
 check_headers(check-headers db
   GLOB_RECURSE ${CMAKE_CURRENT_SOURCE_DIR}/*.hh)

db/commitlog/commitlog.cc

@@ -3461,12 +3461,15 @@ db::commitlog::read_log_file(const replay_state& state, sstring filename, sstrin
             clogger.debug("Read {} bytes of data ({}, {})", size, pos, rem);
 
             while (rem < size) {
+                const auto initial_size = initial.size_bytes();
+
                 if (eof) {
-                    auto reason = fmt::format("unexpected EOF, rem={}, size={}", rem, size);
+                    auto reason = fmt::format("unexpected EOF, pos={}, rem={}, size={}, alignment={}, initial_size={}",
+                            pos, rem, size, alignment, initial_size);
                     throw segment_truncation(std::move(reason), block_boundry);
                 }
 
-                auto block_size = alignment - initial.size_bytes();
+                auto block_size = alignment - initial_size;
                 // using a stream is perhaps not 100% effective, but we need to 
                 // potentially address data in pages smaller than the current 
                 // disk/fs we are reading from can handle (but please no). 
@@ -3474,8 +3477,9 @@ db::commitlog::read_log_file(const replay_state& state, sstring filename, sstrin
 
                 if (tmp.size_bytes() == 0) {
                     eof = true;
-                    auto reason = fmt::format("read 0 bytes, while tried to read {} bytes. rem={}, size={}",
+                    auto reason = fmt::format("read 0 bytes, while tried to read {} bytes. "
-                            block_size, rem, size);
+                            "pos={}, rem={}, size={}, alignment={}, initial_size={}",
+                            block_size, pos, rem, size, alignment, initial_size);
                     throw segment_truncation(std::move(reason), block_boundry);
                 }
 
@@ -3511,13 +3515,13 @@ db::commitlog::read_log_file(const replay_state& state, sstring filename, sstrin
                     auto checksum = crc.checksum();
 
                     if (check != checksum) {
-                        auto reason = fmt::format("checksums do not match: {:x} vs. {:x}. rem={}, size={}",
+                        auto reason = fmt::format("checksums do not match: {:x} vs. {:x}. pos={}, rem={}, size={}, alignment={}, initial_size={}",
-                                check, checksum, rem, size);
+                                check, checksum, pos, rem, size, alignment, initial_size);
                         throw segment_data_corruption_error(std::move(reason), alignment);
                     }
                     if (id != this->id) {
-                        auto reason = fmt::format("IDs do not match: {} vs. {}. rem={}, size={}",
+                        auto reason = fmt::format("IDs do not match: {} vs. {}. pos={}, rem={}, size={}, alignment={}, initial_size={}",
-                                id, this->id, rem, size);
+                                id, this->id, pos, rem, size, alignment, initial_size);
                         throw segment_truncation(std::move(reason), pos + rem);
                     }
                 }
@@ -3626,6 +3630,10 @@ db::commitlog::read_log_file(const replay_state& state, sstring filename, sstrin
             auto old = pos;
             pos = next_pos(off);
             clogger.trace("Pos {} -> {} ({})", old, pos, off);
+            // #24346 check eof status whenever we move file pos.
+            if (pos >= file_size) {
+                eof = true;
+            }
         }
 
         future<> read_entry() {

db/config.cc

@@ -36,6 +36,7 @@
 #include "sstables/compressor.hh"
 #include "utils/log.hh"
 #include "service/tablet_allocator_fwd.hh"
+#include "backlog_controller_fwd.hh"
 #include "utils/config_file_impl.hh"
 #include "exceptions/exceptions.hh"
 #include <seastar/core/metrics_api.hh>
@@ -630,6 +631,8 @@ db::config::config(std::shared_ptr<db::extensions> exts)
         "If set to higher than 0, ignore the controller's output and set the memtable shares statically. Do not set this unless you know what you are doing and suspect a problem in the controller. This option will be retired when the controller reaches more maturity.")
     , compaction_static_shares(this, "compaction_static_shares", liveness::LiveUpdate, value_status::Used, 0,
         "If set to higher than 0, ignore the controller's output and set the compaction shares statically. Do not set this unless you know what you are doing and suspect a problem in the controller. This option will be retired when the controller reaches more maturity.")
+    , compaction_max_shares(this, "compaction_max_shares", liveness::LiveUpdate, value_status::Used, default_compaction_maximum_shares,
+        "Set the maximum shares of regular compaction to the specific value. Do not set this unless you know what you are doing and suspect a problem in the controller. This option will be retired when the controller reaches more maturity.")
     , compaction_enforce_min_threshold(this, "compaction_enforce_min_threshold", liveness::LiveUpdate, value_status::Used, false,
         "If set to true, enforce the min_threshold option for compactions strictly. If false (default), Scylla may decide to compact even if below min_threshold.")
     , compaction_flush_all_tables_before_major_seconds(this, "compaction_flush_all_tables_before_major_seconds", value_status::Used, 86400,
@@ -1035,8 +1038,9 @@ db::config::config(std::shared_ptr<db::extensions> exts)
         "Controls whether traffic between nodes is compressed. The valid values are:\n"
         "* all: All traffic is compressed.\n"
         "* dc : Traffic between data centers is compressed.\n"
+        "* rack : Traffic between racks is compressed.\n"
         "* none : No compression.",
-        {"all", "dc", "none"})
+        {"all", "dc", "rack", "none"})
     , internode_compression_zstd_max_cpu_fraction(this, "internode_compression_zstd_max_cpu_fraction", liveness::LiveUpdate, value_status::Used, 0.000,
         "ZSTD compression of RPC will consume at most this fraction of each internode_compression_zstd_quota_refresh_period_ms time slice.\n"
         "If you wish to try out zstd for RPC compression, 0.05 is a reasonable starting point.")
@@ -1168,6 +1172,17 @@ db::config::config(std::shared_ptr<db::extensions> exts)
         "* default_weight: (Default: 1 **)  How many requests are handled during each turn of the RoundRobin.\n"
         "* weights: (Default: Keyspace: 1)  Takes a list of keyspaces. It sets how many requests are handled during each turn of the RoundRobin, based on the request_scheduler_id.")
     /**
+    * @Group Vector search settings
+    * @GroupDescription Settings for configuring and tuning vector search functionality.
+    */
+    , vector_store_primary_uri(this, "vector_store_primary_uri", liveness::LiveUpdate, value_status::Used, "",
+        "A comma-separated list of primary vector store node URIs. These nodes are preferred for vector search operations.")
+    , vector_store_secondary_uri(this, "vector_store_secondary_uri", liveness::LiveUpdate, value_status::Used, "",
+        "A comma-separated list of secondary vector store node URIs. These nodes are used as a fallback when all primary nodes are unavailable, and are typically located in a different availability zone for high availability.")
+    , vector_store_encryption_options(this, "vector_store_encryption_options", value_status::Used, {},
+        "Options for encrypted connections to the vector store. These options are used for HTTPS URIs in `vector_store_primary_uri` and `vector_store_secondary_uri`. The available options are:\n"
+        "* truststore: (Default: <not set, use system truststore>) Location of the truststore containing the trusted certificate for authenticating remote servers.")
+    /**
     * @Group Security properties
     * @GroupDescription Server and client security settings.
     */
@@ -1429,6 +1444,11 @@ db::config::config(std::shared_ptr<db::extensions> exts)
     , alternator_warn_authorization(this, "alternator_warn_authorization", liveness::LiveUpdate, value_status::Used, false, "Count and log warnings about failed authentication or authorization")
     , alternator_write_isolation(this, "alternator_write_isolation", value_status::Used, "", "Default write isolation policy for Alternator.")
     , alternator_streams_time_window_s(this, "alternator_streams_time_window_s", value_status::Used, 10, "CDC query confidence window for alternator streams.")
+    , alternator_streams_increased_compatibility(this, "alternator_streams_increased_compatibility", liveness::LiveUpdate, value_status::Used, false,
+        "Increases compatibility with DynamoDB Streams at the cost of performance. "
+        "If enabled, Alternator compares the existing item with the new one during "
+        "data-modifying operations to determine which event type should be emitted. "
+        "This penalty is incurred only for tables with Alternator Streams enabled.")
     , alternator_timeout_in_ms(this, "alternator_timeout_in_ms", liveness::LiveUpdate, value_status::Used, 10000,
         "The server-side timeout for completing Alternator API requests.")
     , alternator_ttl_period_in_seconds(this, "alternator_ttl_period_in_seconds", value_status::Used,
@@ -1450,7 +1470,6 @@ db::config::config(std::shared_ptr<db::extensions> exts)
     , alternator_max_expression_cache_entries_per_shard(this, "alternator_max_expression_cache_entries_per_shard", liveness::LiveUpdate, value_status::Used, 2000, "Maximum number of cached parsed request expressions, per shard.")
     , alternator_max_users_query_size_in_trace_output(this, "alternator_max_users_query_size_in_trace_output", liveness::LiveUpdate, value_status::Used, uint64_t(4096),
             "Maximum size of user's command in trace output (`alternator_op` entry). Larger traces will be truncated and have `<truncated>` message appended - which doesn't count to the maximum limit.")
-    , vector_store_primary_uri(this, "vector_store_primary_uri", liveness::LiveUpdate, value_status::Used, "", "A comma-separated list of vector store node URIs. If not set, vector search is disabled.")
     , abort_on_ebadf(this, "abort_on_ebadf", value_status::Used, true, "Abort the server on incorrect file descriptor access. Throws exception when disabled.")
     , sanitizer_report_backtrace(this, "sanitizer_report_backtrace", value_status::Used, false,
             "In debug mode, report log-structured allocator sanitizer violations with a backtrace. Slow.")

db/config.hh

@@ -189,6 +189,7 @@ public:
     named_value<bool> auto_adjust_flush_quota;
     named_value<float> memtable_flush_static_shares;
     named_value<float> compaction_static_shares;
+    named_value<float> compaction_max_shares;
     named_value<bool> compaction_enforce_min_threshold;
     named_value<uint32_t> compaction_flush_all_tables_before_major_seconds;
     named_value<sstring> cluster_name;
@@ -343,6 +344,9 @@ public:
     named_value<sstring> request_scheduler;
     named_value<sstring> request_scheduler_id;
     named_value<string_map> request_scheduler_options;
+    named_value<sstring> vector_store_primary_uri;
+    named_value<sstring> vector_store_secondary_uri;
+    named_value<string_map> vector_store_encryption_options;
     named_value<sstring> authenticator;
     named_value<sstring> internode_authenticator;
     named_value<sstring> authorizer;
@@ -461,6 +465,7 @@ public:
     named_value<bool> alternator_warn_authorization;
     named_value<sstring> alternator_write_isolation;
     named_value<uint32_t> alternator_streams_time_window_s;
+    named_value<bool> alternator_streams_increased_compatibility;
     named_value<uint32_t> alternator_timeout_in_ms;
     named_value<double> alternator_ttl_period_in_seconds;
     named_value<sstring> alternator_describe_endpoints;
@@ -469,8 +474,6 @@ public:
     named_value<uint32_t> alternator_max_expression_cache_entries_per_shard;
     named_value<uint64_t> alternator_max_users_query_size_in_trace_output;
 
-    named_value<sstring> vector_store_primary_uri;
-
     named_value<bool> abort_on_ebadf;
 
     named_value<bool> sanitizer_report_backtrace;

db/legacy_schema_migrator.cc

@@ -152,8 +152,8 @@ public:
 
             builder.with_version(sm.digest());
 
-            cf_type cf = sstring_to_cf_type(td.get_or("type", sstring("standard")));
+            auto type_str = td.get_or("type", sstring("standard"));
-            if (cf == cf_type::super) {
+            if (type_str == "Super") {
                 fail(unimplemented::cause::SUPER);
             }
 
@@ -284,14 +284,9 @@ public:
                     if (kind_str == "compact_value") {
                         continue;
                     }
-                    if (kind == column_kind::clustering_key) {
+                    if (kind == column_kind::clustering_key && !is_compound) {
-                        if (cf == cf_type::super && component_index != 0) {
                         continue;
                     }
-                        if (cf != cf_type::super && !is_compound) {
-                            continue;
-                        }
-                    }
                 }
 
                 std::optional<index_metadata_kind> index_kind;

db/schema_tables.cc

@@ -143,7 +143,7 @@ static computed_columns_map get_computed_columns(const schema_mutations& sm);
 
 static std::vector<column_definition> create_columns_from_column_rows(
                 const query::result_set& rows, const sstring& keyspace,
-                const sstring& table, bool is_super, column_view_virtual is_view_virtual, const computed_columns_map& computed_columns,
+                const sstring& table, column_view_virtual is_view_virtual, const computed_columns_map& computed_columns,
                 const data_dictionary::user_types_storage& user_types);
 
 
@@ -1804,9 +1804,6 @@ static schema_mutations make_table_mutations(schema_ptr table, api::timestamp_ty
     auto scylla_tables_mutation = make_scylla_tables_mutation(table, timestamp);
 
     list_type_impl::native_type flags;
-    if (table->is_super()) {
-        flags.emplace_back("super");
-    }
     if (table->is_dense()) {
         flags.emplace_back("dense");
     }
@@ -2280,7 +2277,6 @@ schema_ptr create_table_from_mutations(const schema_ctxt& ctxt, schema_mutations
     auto id = table_id(table_row.get_nonnull<utils::UUID>("id"));
     schema_builder builder{ks_name, cf_name, id};
 
-    auto cf = cf_type::standard;
     auto is_dense = false;
     auto is_counter = false;
     auto is_compound = false;
@@ -2289,7 +2285,6 @@ schema_ptr create_table_from_mutations(const schema_ctxt& ctxt, schema_mutations
     if (flags) {
         for (auto& s : *flags) {
             if (s == "super") {
-                // cf = cf_type::super;
                 fail(unimplemented::cause::SUPER);
             } else if (s == "dense") {
                 is_dense = true;
@@ -2305,9 +2300,7 @@ schema_ptr create_table_from_mutations(const schema_ctxt& ctxt, schema_mutations
     std::vector<column_definition> column_defs = create_columns_from_column_rows(
             query::result_set(sm.columns_mutation()),
             ks_name,
-            cf_name,/*,
+            cf_name,
-            fullRawComparator, */
-            cf == cf_type::super,
             column_view_virtual::no,
             computed_columns,
             user_types);
@@ -2486,9 +2479,7 @@ static computed_columns_map get_computed_columns(const schema_mutations& sm) {
 static std::vector<column_definition> create_columns_from_column_rows(
                                                                const query::result_set& rows,
                                                                const sstring& keyspace,
-                                                               const sstring& table, /*,
+                                                               const sstring& table,
-                                                               AbstractType<?> rawComparator, */
-                                                               bool is_super,
                                                                column_view_virtual is_view_virtual,
                                                                const computed_columns_map& computed_columns,
                                                                const data_dictionary::user_types_storage& user_types)
@@ -2565,12 +2556,12 @@ static schema_builder prepare_view_schema_builder_from_mutations(const schema_ct
     }
 
     auto computed_columns = get_computed_columns(sm);
-    auto column_defs = create_columns_from_column_rows(query::result_set(sm.columns_mutation()), ks_name, cf_name, false, column_view_virtual::no, computed_columns, user_types);
+    auto column_defs = create_columns_from_column_rows(query::result_set(sm.columns_mutation()), ks_name, cf_name, column_view_virtual::no, computed_columns, user_types);
     for (auto&& cdef : column_defs) {
         builder.with_column_ordered(cdef);
     }
     if (sm.view_virtual_columns_mutation()) {
-        column_defs = create_columns_from_column_rows(query::result_set(*sm.view_virtual_columns_mutation()), ks_name, cf_name, false, column_view_virtual::yes, computed_columns, user_types);
+        column_defs = create_columns_from_column_rows(query::result_set(*sm.view_virtual_columns_mutation()), ks_name, cf_name, column_view_virtual::yes, computed_columns, user_types);
         for (auto&& cdef : column_defs) {
             builder.with_column_ordered(cdef);
         }

db/system_keyspace.cc

@@ -766,9 +766,6 @@ schema_ptr system_keyspace::size_estimates() {
         "partitions larger than specified threshold"
         );
         builder.set_gc_grace_seconds(0);
-        // FIXME re-enable caching for this and the other two
-        // system.large_* tables once
-        // https://github.com/scylladb/scylla/issues/3288 is fixed
         builder.set_caching_options(caching_options::get_disabled_caching_options());
         builder.with_hash_version();
         return builder.build(schema_builder::compact_storage::no);
@@ -1667,7 +1664,7 @@ schema_ptr system_keyspace::view_building_tasks() {
                 .with_column("key", utf8_type, column_kind::partition_key)
                 .with_column("id", timeuuid_type, column_kind::clustering_key)
                 .with_column("type", utf8_type)
-                .with_column("state", utf8_type)
+                .with_column("aborted", boolean_type)
                 .with_column("base_id", uuid_type)
                 .with_column("view_id", uuid_type)
                 .with_column("last_token", long_type)
@@ -3062,14 +3059,14 @@ future<mutation> system_keyspace::make_remove_view_build_status_on_host_mutation
 static constexpr auto VIEW_BUILDING_KEY = "view_building";
 
 future<db::view::building_tasks> system_keyspace::get_view_building_tasks() {
-    static const sstring query = format("SELECT id, type, state, base_id, view_id, last_token, host_id, shard FROM {}.{} WHERE key = '{}'", NAME, VIEW_BUILDING_TASKS, VIEW_BUILDING_KEY);
+    static const sstring query = format("SELECT id, type, aborted, base_id, view_id, last_token, host_id, shard FROM {}.{} WHERE key = '{}'", NAME, VIEW_BUILDING_TASKS, VIEW_BUILDING_KEY);
     using namespace db::view;
 
     building_tasks tasks;
     co_await _qp.query_internal(query, [&] (const cql3::untyped_result_set_row& row) -> future<stop_iteration> {
         auto id = row.get_as<utils::UUID>("id");
         auto type = task_type_from_string(row.get_as<sstring>("type"));
-        auto state = task_state_from_string(row.get_as<sstring>("state"));
+        auto aborted = row.get_as<bool>("aborted");
         auto base_id = table_id(row.get_as<utils::UUID>("base_id"));
         auto view_id = row.get_opt<utils::UUID>("view_id").transform([] (const utils::UUID& uuid) { return table_id(uuid); });
         auto last_token = dht::token::from_int64(row.get_as<int64_t>("last_token"));
@@ -3077,7 +3074,7 @@ future<db::view::building_tasks> system_keyspace::get_view_building_tasks() {
         auto shard = unsigned(row.get_as<int32_t>("shard"));
 
         locator::tablet_replica replica{host_id, shard};
-        view_building_task task{id, type, state, base_id, view_id, replica, last_token};
+        view_building_task task{id, type, aborted, base_id, view_id, replica, last_token};
 
         switch (type) {
         case db::view::view_building_task::task_type::build_range:
@@ -3096,7 +3093,7 @@ future<db::view::building_tasks> system_keyspace::get_view_building_tasks() {
 }
 
 future<mutation> system_keyspace::make_view_building_task_mutation(api::timestamp_type ts, const db::view::view_building_task& task) {
-    static const sstring stmt = format("INSERT INTO {}.{}(key, id, type, state, base_id, view_id, last_token, host_id, shard) VALUES ('{}', ?, ?, ?, ?, ?, ?, ?, ?)", NAME, VIEW_BUILDING_TASKS, VIEW_BUILDING_KEY);
+    static const sstring stmt = format("INSERT INTO {}.{}(key, id, type, aborted, base_id, view_id, last_token, host_id, shard) VALUES ('{}', ?, ?, ?, ?, ?, ?, ?, ?)", NAME, VIEW_BUILDING_TASKS, VIEW_BUILDING_KEY);
     using namespace db::view;
 
     data_value_or_unset view_id = unset_value{};
@@ -3107,7 +3104,7 @@ future<mutation> system_keyspace::make_view_building_task_mutation(api::timestam
         view_id = data_value(task.view_id->uuid());
     }
     auto muts = co_await _qp.get_mutations_internal(stmt, internal_system_query_state(), ts, {
-            task.id, task_type_to_sstring(task.type), task_state_to_sstring(task.state),
+            task.id, task_type_to_sstring(task.type), task.aborted,
             task.base_id.uuid(), view_id, dht::token::to_int64(task.last_token),
             task.replica.host.uuid(), int32_t(task.replica.shard)
     });
@@ -3117,18 +3114,6 @@ future<mutation> system_keyspace::make_view_building_task_mutation(api::timestam
     co_return std::move(muts[0]);
 }
 
-future<mutation> system_keyspace::make_update_view_building_task_state_mutation(api::timestamp_type ts, utils::UUID id, db::view::view_building_task::task_state state) {
-    static const sstring stmt = format("UPDATE {}.{} SET state = ? WHERE key = '{}' AND id = ?", NAME, VIEW_BUILDING_TASKS, VIEW_BUILDING_KEY);
-
-    auto muts = co_await _qp.get_mutations_internal(stmt, internal_system_query_state(), ts, {
-            task_state_to_sstring(state), id
-    });
-    if (muts.size() != 1) {
-        on_internal_error(slogger, fmt::format("expected 1 mutation got {}", muts.size()));
-    }
-    co_return std::move(muts[0]);
-}
-
 future<mutation> system_keyspace::make_remove_view_building_task_mutation(api::timestamp_type ts, utils::UUID id) {
     static const sstring stmt = format("DELETE FROM {}.{} WHERE key = '{}' AND id = ?", NAME, VIEW_BUILDING_TASKS, VIEW_BUILDING_KEY);
 

db/system_keyspace.hh

@@ -576,7 +576,6 @@ public:
     // system.view_building_tasks
     future<db::view::building_tasks> get_view_building_tasks();
     future<mutation> make_view_building_task_mutation(api::timestamp_type ts, const db::view::view_building_task& task);
-    future<mutation> make_update_view_building_task_state_mutation(api::timestamp_type ts, utils::UUID id, db::view::view_building_task::task_state state);
     future<mutation> make_remove_view_building_task_mutation(api::timestamp_type ts, utils::UUID id);
 
     // system.scylla_local, view_building_processing_base key

db/view/delete_ghost_rows_visitor.hh

@@ -9,6 +9,8 @@
 #include "query/query-result-reader.hh"
 #include "replica/database_fwd.hh"
 #include "db/timeout_clock.hh"
+#include <seastar/core/future.hh>
+#include <seastar/core/gate.hh>
 
 namespace service {
 class storage_proxy;
@@ -25,8 +27,14 @@ class delete_ghost_rows_visitor {
     replica::table& _view_table;
     schema_ptr _base_schema;
     std::optional<partition_key> _view_pk;
+    db::timeout_semaphore _concurrency_semaphore;
+    seastar::gate _gate;
+    std::exception_ptr& _ex;
+
 public:
-    delete_ghost_rows_visitor(service::storage_proxy& proxy, service::query_state& state, view_ptr view, db::timeout_clock::duration timeout_duration);
+    delete_ghost_rows_visitor(service::storage_proxy& proxy, service::query_state& state, view_ptr view, db::timeout_clock::duration timeout_duration, size_t concurrency, std::exception_ptr& ex);
+    delete_ghost_rows_visitor(delete_ghost_rows_visitor&&) = default;
+    ~delete_ghost_rows_visitor() noexcept;
 
     void add_value(const column_definition& def, query::result_row_view::iterator_type& i) {
     }
@@ -45,6 +53,9 @@ public:
     uint32_t accept_partition_end(const query::result_row_view& static_row) {
         return 0;
     }
+
+private:
+    future<> do_accept_new_row(partition_key pk,  clustering_key ck);
 };
 
 } //namespace db::view

db/view/view.cc

@@ -3597,7 +3597,7 @@ view_updating_consumer::view_updating_consumer(view_update_generator& gen, schem
     })
 { }
 
-delete_ghost_rows_visitor::delete_ghost_rows_visitor(service::storage_proxy& proxy, service::query_state& state, view_ptr view, db::timeout_clock::duration timeout_duration)
+delete_ghost_rows_visitor::delete_ghost_rows_visitor(service::storage_proxy& proxy, service::query_state& state, view_ptr view, db::timeout_clock::duration timeout_duration, size_t concurrency, std::exception_ptr& ex)
         : _proxy(proxy)
         , _state(state)
         , _timeout_duration(timeout_duration)
@@ -3605,8 +3605,20 @@ delete_ghost_rows_visitor::delete_ghost_rows_visitor(service::storage_proxy& pro
         , _view_table(_proxy.get_db().local().find_column_family(view))
         , _base_schema(_proxy.get_db().local().find_schema(_view->view_info()->base_id()))
         , _view_pk()
+        , _concurrency_semaphore(concurrency)
+        , _ex(ex)
 {}
 
+
+delete_ghost_rows_visitor::~delete_ghost_rows_visitor() noexcept {
+    try {
+        _gate.close().get();
+    } catch (...) {
+        // Closing the gate should never throw, but if it does anyway, capture the exception.
+        _ex = std::current_exception();
+    }
+}
+
 void delete_ghost_rows_visitor::accept_new_partition(const partition_key& key, uint32_t row_count) {
     SCYLLA_ASSERT(thread::running_in_thread());
     _view_pk = key;
@@ -3614,7 +3626,18 @@ void delete_ghost_rows_visitor::accept_new_partition(const partition_key& key, u
 
 // Assumes running in seastar::thread
 void delete_ghost_rows_visitor::accept_new_row(const clustering_key& ck, const query::result_row_view& static_row, const query::result_row_view& row) {
-    auto view_exploded_pk = _view_pk->explode();
+    auto units = get_units(_concurrency_semaphore, 1).get();
+    (void)seastar::try_with_gate(_gate, [this, pk = _view_pk.value(), units = std::move(units), ck] () mutable {
+        return do_accept_new_row(std::move(pk), std::move(ck)).then_wrapped([this, units = std::move(units)] (future<>&& f) mutable {
+            if (f.failed()) {
+                _ex = f.get_exception();
+            }
+        });
+    });
+}
+
+future<> delete_ghost_rows_visitor::do_accept_new_row(partition_key pk, clustering_key ck) {
+    auto view_exploded_pk = pk.explode();
     auto view_exploded_ck = ck.explode();
     std::vector<bytes> base_exploded_pk(_base_schema->partition_key_size());
     std::vector<bytes> base_exploded_ck(_base_schema->clustering_key_size());
@@ -3649,17 +3672,17 @@ void delete_ghost_rows_visitor::accept_new_row(const clustering_key& ck, const q
             _proxy.get_max_result_size(partition_slice), query::tombstone_limit(_proxy.get_tombstone_limit()));
     auto timeout = db::timeout_clock::now() + _timeout_duration;
     service::storage_proxy::coordinator_query_options opts{timeout, _state.get_permit(), _state.get_client_state(), _state.get_trace_state()};
-    auto base_qr = _proxy.query(_base_schema, command, std::move(partition_ranges), db::consistency_level::ALL, opts).get();
+    auto base_qr = co_await _proxy.query(_base_schema, command, std::move(partition_ranges), db::consistency_level::ALL, opts);
     query::result& result = *base_qr.query_result;
-    auto delete_ghost_row = [&]() {
+    auto delete_ghost_row = [&]() -> future<> {
-        mutation m(_view, *_view_pk);
+        mutation m(_view, pk);
         auto& row = m.partition().clustered_row(*_view, ck);
         row.apply(tombstone(api::new_timestamp(), gc_clock::now()));
         timeout = db::timeout_clock::now() + _timeout_duration;
-        _proxy.mutate({m}, db::consistency_level::ALL, timeout, _state.get_trace_state(), empty_service_permit(), db::allow_per_partition_rate_limit::no).get();
+        return _proxy.mutate({m}, db::consistency_level::ALL, timeout, _state.get_trace_state(), empty_service_permit(), db::allow_per_partition_rate_limit::no);
     };
     if (result.row_count().value_or(0) == 0) {
-        delete_ghost_row();
+        co_await delete_ghost_row();
     } else if (!view_key_cols_not_in_base_key.empty()) {
         if (result.row_count().value_or(0) != 1) {
             on_internal_error(vlogger, format("Got multiple base rows corresponding to a single view row when pruning {}.{}", _view->ks_name(), _view->cf_name()));
@@ -3669,7 +3692,7 @@ void delete_ghost_rows_visitor::accept_new_row(const clustering_key& ck, const q
         for (const auto& [col_def, col_val] : view_key_cols_not_in_base_key) {
             const data_value* base_val = base_row.get_data_value(col_def->name_as_text());
             if (!base_val || base_val->is_null() || col_val != base_val->serialize_nonnull()) {
-                delete_ghost_row();
+                co_await delete_ghost_row();
                 break;
             }
         }

db/view/view_building_coordinator.cc

@@ -104,6 +104,8 @@ future<> view_building_coordinator::run() {
         _vb_sm.event.broadcast();
     });
 
+    auto finished_tasks_gc_fiber = finished_task_gc_fiber();
+
     while (!_as.abort_requested()) {
         co_await utils::get_local_injector().inject("view_building_coordinator_pause_main_loop", utils::wait_for_message(std::chrono::minutes(2)));
         if (utils::get_local_injector().enter("view_building_coordinator_skip_main_loop")) {
@@ -121,12 +123,7 @@ future<> view_building_coordinator::run() {
                 continue;
             }
 
-            auto started_new_work = co_await work_on_view_building(std::move(*guard_opt));
+            co_await work_on_view_building(std::move(*guard_opt));
-            if (started_new_work) {
-                // If any tasks were started, do another iteration, so the coordinator can attach itself to the tasks (via RPC)
-                vbc_logger.debug("view building coordinator started new tasks, do next iteration without waiting for event");
-                continue;
-            }
             co_await await_event();
         } catch (...) {
             handle_coordinator_error(std::current_exception());
@@ -142,6 +139,66 @@ future<> view_building_coordinator::run() {
             }
         }
     }
+
+    co_await std::move(finished_tasks_gc_fiber);
+}
+
+future<> view_building_coordinator::finished_task_gc_fiber() {
+    static auto task_gc_interval = 200ms;
+
+    while (!_as.abort_requested()) {
+        try {
+            co_await clean_finished_tasks();
+            co_await sleep_abortable(task_gc_interval, _as);
+        } catch (abort_requested_exception&) {
+            vbc_logger.debug("view_building_coordinator::finished_task_gc_fiber got abort_requested_exception");
+        } catch (service::group0_concurrent_modification&) {
+            vbc_logger.info("view_building_coordinator::finished_task_gc_fiber got group0_concurrent_modification");
+        } catch (raft::request_aborted&) {
+            vbc_logger.debug("view_building_coordinator::finished_task_gc_fiber got raft::request_aborted");
+        } catch (service::term_changed_error&) {
+            vbc_logger.debug("view_building_coordinator::finished_task_gc_fiber notices term change {} -> {}", _term, _raft.get_current_term());
+        } catch (raft::commit_status_unknown&) {
+            vbc_logger.warn("view_building_coordinator::finished_task_gc_fiber got raft::commit_status_unknown");
+        } catch (...) {
+            vbc_logger.error("view_building_coordinator::finished_task_gc_fiber got error: {}", std::current_exception());
+        }
+    }
+}
+
+future<> view_building_coordinator::clean_finished_tasks() {
+    // Avoid acquiring a group0 operation if there are no tasks.
+    if (_finished_tasks.empty()) {
+        co_return;
+    }
+
+    auto guard = co_await start_operation();
+    auto lock = co_await get_unique_lock(_mutex);
+
+    if (!_vb_sm.building_state.currently_processed_base_table || std::ranges::all_of(_finished_tasks, [] (auto& e) { return e.second.empty(); })) {
+        co_return;
+    }
+
+    view_building_task_mutation_builder builder(guard.write_timestamp());
+    for (auto& [replica, tasks]: _finished_tasks) {
+        for (auto& task_id: tasks) {
+            // The task might be aborted in the meantime. In this case we cannot remove it because we need it to create a new task.
+            //
+            // TODO: When we're aborting a view building task (for instance due to tablet migration),
+            //       we can look if we already finished it (check if it's in `_finished_tasks`).
+            //       If yes, we can just remove it instead of aborting it.
+            auto task_opt = _vb_sm.building_state.get_task(*_vb_sm.building_state.currently_processed_base_table, replica, task_id);
+            if (task_opt && !task_opt->get().aborted) {
+                builder.del_task(task_id);
+                vbc_logger.debug("Removing finished task with ID: {}", task_id);
+            }
+        }
+    }
+
+    co_await commit_mutations(std::move(guard), {builder.build()}, "remove finished view building tasks");
+    for (auto& [_, tasks_set]: _finished_tasks) {
+        tasks_set.clear();
+    }
 }
 
 future<std::optional<service::group0_guard>> view_building_coordinator::update_state(service::group0_guard guard) {
@@ -301,18 +358,16 @@ future<> view_building_coordinator::update_views_statuses(const service::group0_
     }
 }
 
-future<bool> view_building_coordinator::work_on_view_building(service::group0_guard guard) {
+future<> view_building_coordinator::work_on_view_building(service::group0_guard guard) {
     if (!_vb_sm.building_state.currently_processed_base_table) {
         vbc_logger.debug("No base table is selected, nothing to do.");
-        co_return false;
+        co_return;
     }
 
-    utils::chunked_vector<mutation> muts;
+    // Acquire unique lock of `_finished_tasks` to ensure each replica has its own entry in it
-    std::unordered_set<locator::tablet_replica> _remote_work_keys_to_erase;
+    // and to select tasks for them.
+    auto lock = co_await get_unique_lock(_mutex);
     for (auto& replica: get_replicas_with_tasks()) {
-        // Check whether the coordinator already waits for the remote work on the replica to be finished.
-        // If so: check if the work is done and and remove the shared_future, skip this replica otherwise.
-        bool skip_work_on_this_replica = false;
         if (_remote_work.contains(replica)) {
             if (!_remote_work[replica].available()) {
                 vbc_logger.debug("Replica {} is still doing work", replica);
@@ -320,22 +375,8 @@ future<bool> view_building_coordinator::work_on_view_building(service::group0_gu
             }
 
             auto remote_results_opt = co_await _remote_work[replica].get_future();
-            if (remote_results_opt) {
-                auto results_muts = co_await update_state_after_work_is_done(guard, replica, std::move(*remote_results_opt));
-                muts.insert(muts.end(), std::make_move_iterator(results_muts.begin()), std::make_move_iterator(results_muts.end()));
-                // If the replica successfully finished its work, we need to commit mutations generated above before selecting next task
-                skip_work_on_this_replica = !results_muts.empty();
-            }
-
-            // If there were no mutations for this replica, we can just remove the entry from `_remote_work` map
-            // and start new work in the same iteration.
-            // Otherwise, the entry needs to be removed after the mutations are committed successfully.
-            if (skip_work_on_this_replica) {
-                _remote_work_keys_to_erase.insert(replica);
-            } else {
             _remote_work.erase(replica);
         }
-        }
 
         const bool ignore_gossiper = utils::get_local_injector().enter("view_building_coordinator_ignore_gossiper");
         if (!_gossiper.is_alive(replica.host) && !ignore_gossiper) {
@@ -343,31 +384,16 @@ future<bool> view_building_coordinator::work_on_view_building(service::group0_gu
             continue;
         }
 
-        if (skip_work_on_this_replica) {
+        if (!_finished_tasks.contains(replica)) {
-            continue;
+            _finished_tasks.insert({replica, {}});
         }
 
-        if (auto already_started_ids = _vb_sm.building_state.get_started_tasks(*_vb_sm.building_state.currently_processed_base_table, replica); !already_started_ids.empty()) {
+        if (auto todo_ids = select_tasks_for_replica(replica); !todo_ids.empty()) {
-            // If the replica has any task in `STARTED` state, attach the coordinator to the work.
+            start_remote_worker(replica, std::move(todo_ids));
-            attach_to_started_tasks(replica, std::move(already_started_ids));
-        } else if (auto todo_ids = select_tasks_for_replica(replica); !todo_ids.empty()) {
-            // If the replica has no started tasks and there are tasks to do, mark them as started.
-            // The coordinator will attach itself to the work in next iteration.
-            auto new_mutations = co_await start_tasks(guard, std::move(todo_ids));
-            muts.insert(muts.end(), std::make_move_iterator(new_mutations.begin()), std::make_move_iterator(new_mutations.end()));
         } else {
             vbc_logger.debug("Nothing to do for replica {}", replica);
         }
     }
-
-    if (!muts.empty()) {
-        co_await commit_mutations(std::move(guard), std::move(muts), "start view building tasks");
-        for (auto& key: _remote_work_keys_to_erase) {
-            _remote_work.erase(key);
-        }
-        co_return true;
-    }
-    co_return false;
 }
 
 std::set<locator::tablet_replica> view_building_coordinator::get_replicas_with_tasks() {
@@ -390,7 +416,7 @@ std::vector<utils::UUID> view_building_coordinator::select_tasks_for_replica(loc
     // Select only building tasks and return theirs ids
     auto filter_building_tasks = [] (const std::vector<view_building_task>& tasks) -> std::vector<utils::UUID> {
         return tasks | std::views::filter([] (const view_building_task& t) {
-            return t.type == view_building_task::task_type::build_range && t.state == view_building_task::task_state::idle;
+            return t.type == view_building_task::task_type::build_range && !t.aborted;
         }) | std::views::transform([] (const view_building_task& t) {
             return t.id;
         }) | std::ranges::to<std::vector>();
@@ -404,7 +430,29 @@ std::vector<utils::UUID> view_building_coordinator::select_tasks_for_replica(loc
     }
 
     auto& tablet_map = _db.get_token_metadata().tablets().get_tablet_map(*_vb_sm.building_state.currently_processed_base_table);
-    for (auto& [token, tasks]: _vb_sm.building_state.collect_tasks_by_last_token(*_vb_sm.building_state.currently_processed_base_table, replica)) {
+    auto tasks_by_last_token = _vb_sm.building_state.collect_tasks_by_last_token(*_vb_sm.building_state.currently_processed_base_table, replica);
+
+    // Remove completed tasks in `_finished_tasks` from `tasks_by_last_token`
+    auto it = tasks_by_last_token.begin();
+    while (it != tasks_by_last_token.end()) {
+        auto task_it = it->second.begin();
+        while (task_it != it->second.end()) {
+            if (_finished_tasks.at(replica).contains(task_it->id)) {
+                task_it = it->second.erase(task_it);
+            } else {
+                ++task_it;
+            }
+        }
+
+        // Remove the entry from `tasks_by_last_token` if its vector is empty
+        if (it->second.empty()) {
+            it = tasks_by_last_token.erase(it);
+        } else {
+            ++it;
+        }
+    }
+
+    for (auto& [token, tasks]: tasks_by_last_token) {
         auto tid = tablet_map.get_tablet_id(token);
         if (tablet_map.get_tablet_transition_info(tid)) {
             vbc_logger.debug("Tablet {} on replica {} is in transition.", tid, replica);
@@ -416,7 +464,7 @@ std::vector<utils::UUID> view_building_coordinator::select_tasks_for_replica(loc
             return building_tasks;
         } else {
             return tasks | std::views::filter([] (const view_building_task& t) {
-                return t.state == view_building_task::task_state::idle;
+                return !t.aborted;
             }) | std::views::transform([] (const view_building_task& t) {
                 return t.id;
             }) | std::ranges::to<std::vector>();
@@ -426,32 +474,21 @@ std::vector<utils::UUID> view_building_coordinator::select_tasks_for_replica(loc
     return {};
 }
 
-future<utils::chunked_vector<mutation>> view_building_coordinator::start_tasks(const service::group0_guard& guard, std::vector<utils::UUID> tasks) {
+void view_building_coordinator::start_remote_worker(const locator::tablet_replica& replica, std::vector<utils::UUID> tasks) {
-    vbc_logger.info("Starting tasks {}", tasks);
-
-    utils::chunked_vector<mutation> muts;
-    for (auto& t: tasks) {
-        auto mut = co_await _sys_ks.make_update_view_building_task_state_mutation(guard.write_timestamp(), t, view_building_task::task_state::started);
-        muts.push_back(std::move(mut));
-    }
-    co_return muts;
-}
-
-void view_building_coordinator::attach_to_started_tasks(const locator::tablet_replica& replica, std::vector<utils::UUID> tasks) {
     vbc_logger.debug("Attaching to started tasks {} on replica {}", tasks, replica);
-    shared_future<std::optional<remote_work_results>> work = work_on_tasks(replica, std::move(tasks));
+    shared_future<std::optional<std::vector<utils::UUID>>> work = work_on_tasks(replica, std::move(tasks));
     _remote_work.insert({replica, std::move(work)});
 }
 
-future<std::optional<view_building_coordinator::remote_work_results>> view_building_coordinator::work_on_tasks(locator::tablet_replica replica, std::vector<utils::UUID> tasks) {
+future<std::optional<std::vector<utils::UUID>>> view_building_coordinator::work_on_tasks(locator::tablet_replica replica, std::vector<utils::UUID> tasks) {
     constexpr auto backoff_duration = std::chrono::seconds(1);
     static thread_local logger::rate_limit rate_limit{backoff_duration};
 
-    std::vector<view_task_result> remote_results;
+    std::vector<utils::UUID> remote_results;
     bool rpc_failed = false;
 
     try {
-        remote_results = co_await ser::view_rpc_verbs::send_work_on_view_building_tasks(&_messaging, replica.host, _as, tasks);
+        remote_results = co_await ser::view_rpc_verbs::send_work_on_view_building_tasks(&_messaging, replica.host, _as, _term, replica.shard, tasks);
     } catch (...) {
         vbc_logger.log(log_level::warn, rate_limit, "Work on tasks {} on replica {}, failed with error: {}",
                 tasks, replica, std::current_exception());
@@ -464,44 +501,14 @@ future<std::optional<view_building_coordinator::remote_work_results>> view_build
         co_return std::nullopt;
     }
 
-    if (tasks.size() != remote_results.size()) {
+    // In `view_building_coordinator::work_on_view_building()` we made sure that,
-        on_internal_error(vbc_logger, fmt::format("Number of tasks ({}) and results ({}) do not match for replica {}", tasks.size(), remote_results.size(), replica));
+    // each replica has its own entry in the `_finished_tasks`, so now we can just take a shared lock
-    }
+    // and insert its of finished tasks to this replica bucket as there is at most one instance of this method for each replica.
+    auto lock = co_await get_shared_lock(_mutex);
+    _finished_tasks.at(replica).insert_range(remote_results);
 
-    remote_work_results results;
-    for (size_t i = 0; i < tasks.size(); ++i) {
-        results.push_back({tasks[i], remote_results[i]});
-    }
     _vb_sm.event.broadcast();
-    co_return results;
+    co_return remote_results;
-}
-
-// Mark finished task as done (remove them from the table).
-// Retry failed tasks if possible (if failed tasks wasn't aborted).
-future<utils::chunked_vector<mutation>> view_building_coordinator::update_state_after_work_is_done(const service::group0_guard& guard, const locator::tablet_replica& replica, view_building_coordinator::remote_work_results results) {
-    vbc_logger.debug("Got results from replica {}: {}", replica, results);
-
-    utils::chunked_vector<mutation> muts;
-    for (auto& result: results) {
-        vbc_logger.info("Task {} was finished with result: {}", result.first, result.second);
-
-        if (!_vb_sm.building_state.currently_processed_base_table) {
-            continue;
-        }
-
-        // A task can be aborted by deleting it or by setting its state to `ABORTED`.
-        // If the task was aborted by changing the state,
-        // we shouldn't remove it here because it might be needed
-        // to generate updated after tablet operation (migration/resize)
-        // is finished.
-        auto task_opt = _vb_sm.building_state.get_task(*_vb_sm.building_state.currently_processed_base_table, replica, result.first);
-        if (task_opt && task_opt->get().state != view_building_task::task_state::aborted) {
-            // Otherwise, the task was completed successfully and we can remove it.
-            auto delete_mut = co_await _sys_ks.make_remove_view_building_task_mutation(guard.write_timestamp(), result.first);
-            muts.push_back(std::move(delete_mut));
-        }
-    }
-    co_return muts;
 }
 
 future<> view_building_coordinator::stop() {
@@ -531,7 +538,7 @@ void view_building_coordinator::generate_tablet_migration_updates(utils::chunked
     auto create_task_copy_on_pending_replica = [&] (const view_building_task& task) {
         auto new_id = builder.new_id();
         builder.set_type(new_id, task.type)
-                .set_state(new_id, view_building_task::task_state::idle)
+                .set_aborted(new_id, false)
                 .set_base_id(new_id, task.base_id)
                 .set_last_token(new_id, task.last_token)
                 .set_replica(new_id, *trinfo.pending_replica);
@@ -599,7 +606,7 @@ void view_building_coordinator::generate_tablet_resize_updates(utils::chunked_ve
     auto create_task_copy = [&] (const view_building_task& task, dht::token last_token) -> utils::UUID {
         auto new_id = builder.new_id();
         builder.set_type(new_id, task.type)
-                .set_state(new_id, view_building_task::task_state::idle)
+                .set_aborted(new_id, false)
                 .set_base_id(new_id, task.base_id)
                 .set_last_token(new_id, last_token)
                 .set_replica(new_id, task.replica);
@@ -668,7 +675,7 @@ void view_building_coordinator::abort_tasks(utils::chunked_vector<canonical_muta
     auto abort_task_map = [&] (const task_map& task_map) {
         for (auto& [id, _]: task_map) {
             vbc_logger.debug("Aborting task {}", id);
-            builder.set_state(id, view_building_task::task_state::aborted);
+            builder.set_aborted(id, true);
         }
     };
 
@@ -698,7 +705,7 @@ void abort_view_building_tasks(const view_building_state_machine& vb_sm,
         for (auto& [id, task]: task_map) {
             if (task.last_token == last_token) {
                 vbc_logger.debug("Aborting task {}", id);
-                builder.set_state(id, view_building_task::task_state::aborted);
+                builder.set_aborted(id, true);
             }
         }
     };
@@ -714,10 +721,10 @@ void abort_view_building_tasks(const view_building_state_machine& vb_sm,
 
 static void rollback_task_map(view_building_task_mutation_builder& builder, const task_map& task_map) {
     for (auto& [id, task]: task_map) {
-        if (task.state == view_building_task::task_state::aborted) {
+        if (task.aborted) {
             auto new_id = builder.new_id();
             builder.set_type(new_id, task.type)
-                .set_state(new_id, view_building_task::task_state::idle)
+                .set_aborted(new_id, false)
                 .set_base_id(new_id, task.base_id)
                 .set_last_token(new_id, task.last_token)
                 .set_replica(new_id, task.replica);

db/view/view_building_coordinator.hh

@@ -54,9 +54,9 @@ class view_building_coordinator : public service::endpoint_lifecycle_subscriber
     const raft::term_t _term;
     abort_source& _as;
 
-
+    std::unordered_map<locator::tablet_replica, shared_future<std::optional<std::vector<utils::UUID>>>> _remote_work;
-    using remote_work_results = std::vector<std::pair<utils::UUID, db::view::view_task_result>>;
+    shared_mutex _mutex; // guards `_finished_tasks` field
-    std::unordered_map<locator::tablet_replica, shared_future<std::optional<remote_work_results>>> _remote_work;
+    std::unordered_map<locator::tablet_replica, std::unordered_set<utils::UUID>> _finished_tasks;
 
 public:
     view_building_coordinator(replica::database& db, raft::server& raft, service::raft_group0& group0,
@@ -86,9 +86,11 @@ private:
     future<> commit_mutations(service::group0_guard guard, utils::chunked_vector<mutation> mutations, std::string_view description);
     void handle_coordinator_error(std::exception_ptr eptr);
 
+    future<> finished_task_gc_fiber();
+    future<> clean_finished_tasks();
+
     future<std::optional<service::group0_guard>> update_state(service::group0_guard guard);
-    // Returns if any new tasks were started
+    future<> work_on_view_building(service::group0_guard guard);
-    future<bool> work_on_view_building(service::group0_guard guard);
 
     future<> mark_view_build_status_started(const service::group0_guard& guard, table_id view_id, utils::chunked_vector<mutation>& out);
     future<> mark_all_remaining_view_build_statuses_started(const service::group0_guard& guard, table_id base_id, utils::chunked_vector<mutation>& out);
@@ -97,10 +99,8 @@ private:
     std::set<locator::tablet_replica> get_replicas_with_tasks();
     std::vector<utils::UUID> select_tasks_for_replica(locator::tablet_replica replica);
 
-    future<utils::chunked_vector<mutation>> start_tasks(const service::group0_guard& guard, std::vector<utils::UUID> tasks);
+    void start_remote_worker(const locator::tablet_replica& replica, std::vector<utils::UUID> tasks);
-    void attach_to_started_tasks(const locator::tablet_replica& replica, std::vector<utils::UUID> tasks);
+    future<std::optional<std::vector<utils::UUID>>> work_on_tasks(locator::tablet_replica replica, std::vector<utils::UUID> tasks);
-    future<std::optional<remote_work_results>> work_on_tasks(locator::tablet_replica replica, std::vector<utils::UUID> tasks);
-    future<utils::chunked_vector<mutation>> update_state_after_work_is_done(const service::group0_guard& guard, const locator::tablet_replica& replica, remote_work_results results);
 };
 
 void abort_view_building_tasks(const db::view::view_building_state_machine& vb_sm,

db/view/view_building_state.cc

@@ -13,10 +13,10 @@ namespace db {
 
 namespace view {
 
-view_building_task::view_building_task(utils::UUID id, task_type type, task_state state, table_id base_id, std::optional<table_id> view_id, locator::tablet_replica replica, dht::token last_token)
+view_building_task::view_building_task(utils::UUID id, task_type type, bool aborted, table_id base_id, std::optional<table_id> view_id, locator::tablet_replica replica, dht::token last_token)
         : id(id)
         , type(type)
-        , state(state)
+        , aborted(aborted)
         , base_id(base_id)
         , view_id(view_id)
         , replica(replica)
@@ -49,30 +49,6 @@ seastar::sstring task_type_to_sstring(view_building_task::task_type type) {
     }
 }
 
-view_building_task::task_state task_state_from_string(std::string_view str) {
-    if (str == "IDLE") {
-        return view_building_task::task_state::idle;
-    }
-    if (str == "STARTED") {
-        return view_building_task::task_state::started;
-    }
-    if (str == "ABORTED") {
-        return view_building_task::task_state::aborted;
-    }
-    throw std::runtime_error(fmt::format("Unknown view building task state: {}", str));
-}
-
-seastar::sstring task_state_to_sstring(view_building_task::task_state state) {
-    switch (state) {
-    case view_building_task::task_state::idle:
-        return "IDLE";
-    case view_building_task::task_state::started:
-        return "STARTED";
-    case view_building_task::task_state::aborted:
-        return "ABORTED";
-    }
-}
-
 std::optional<std::reference_wrapper<const view_building_task>> view_building_state::get_task(table_id base_id, locator::tablet_replica replica, utils::UUID id) const {
     if (!tasks_state.contains(base_id) || !tasks_state.at(base_id).contains(replica)) {
         return {};
@@ -151,46 +127,6 @@ std::map<dht::token, std::vector<view_building_task>> view_building_state::colle
     return tasks;
 }
 
-// Returns all tasks for `_vb_sm.building_state.currently_processed_base_table` and `replica` with `STARTED` state.
-std::vector<utils::UUID> view_building_state::get_started_tasks(table_id base_table_id, locator::tablet_replica replica) const {   
-    if (!tasks_state.contains(base_table_id) || !tasks_state.at(base_table_id).contains(replica)) {
-        // No tasks for this replica
-        return {};
-    }
-
-    std::vector<view_building_task> tasks;
-    auto& replica_tasks = tasks_state.at(base_table_id).at(replica);
-    for (auto& [_, view_tasks]: replica_tasks.view_tasks) {
-        for (auto& [_, task]: view_tasks) {
-            if (task.state == view_building_task::task_state::started) {
-                tasks.push_back(task);
-            }
-        }
-    }
-    for (auto& [_, task]: replica_tasks.staging_tasks) {
-        if (task.state == view_building_task::task_state::started) {
-            tasks.push_back(task);
-        }
-    }
-
-    // All collected tasks should have the same: type, base_id and last_token,
-    // so they can be executed in the same view_building_worker::batch.
-#ifdef SEASTAR_DEBUG
-    if (!tasks.empty()) {
-        auto& task = tasks.front();
-        for (auto& t: tasks) {
-            SCYLLA_ASSERT(task.type == t.type);
-            SCYLLA_ASSERT(task.base_id == t.base_id);
-            SCYLLA_ASSERT(task.last_token == t.last_token);
-        }
-    }
-#endif
-
-    return tasks | std::views::transform([] (const view_building_task& t) {
-        return t.id;
-    }) | std::ranges::to<std::vector>();
-}
-
 }
 
 }

db/view/view_building_state.hh

@@ -39,28 +39,17 @@ struct view_building_task {
         process_staging,
     };
 
-    // When a task is created, it starts with `IDLE` state.
+
-    // Then, the view building coordinator will decide to do the task and it will
-    // set the state to `STARTED`.
-    // When a task is finished the entry is removed.
-    //
-    // If a task is in progress when a tablet operation (migration/resize) starts,
-    // the task's state is set to `ABORTED`.
-    enum class task_state {
-        idle,
-        started,
-        aborted,
-    };
     utils::UUID id;
     task_type type;
-    task_state state;
+    bool aborted;
 
     table_id base_id;
     std::optional<table_id> view_id; // nullopt when task_type is `process_staging`
     locator::tablet_replica replica;
     dht::token last_token;
 
-    view_building_task(utils::UUID id, task_type type, task_state state,
+    view_building_task(utils::UUID id, task_type type, bool aborted,
             table_id base_id, std::optional<table_id> view_id,
             locator::tablet_replica replica, dht::token last_token);
 };
@@ -92,7 +81,6 @@ struct view_building_state {
     std::vector<std::reference_wrapper<const view_building_task>> get_tasks_for_host(table_id base_id, locator::host_id host) const;
     std::map<dht::token, std::vector<view_building_task>> collect_tasks_by_last_token(table_id base_table_id) const;
     std::map<dht::token, std::vector<view_building_task>> collect_tasks_by_last_token(table_id base_table_id, const locator::tablet_replica& replica) const;
-    std::vector<utils::UUID> get_started_tasks(table_id base_table_id, locator::tablet_replica replica) const;
 };
 
 // Represents global state of tablet-based views.
@@ -113,18 +101,8 @@ struct view_building_state_machine {
     condition_variable event;
 };
 
-struct view_task_result {
-    enum class command_status: uint8_t {
-        success = 0,
-        abort = 1,
-    };
-    db::view::view_task_result::command_status status;
-};
-
 view_building_task::task_type task_type_from_string(std::string_view str);
 seastar::sstring task_type_to_sstring(view_building_task::task_type type);
-view_building_task::task_state task_state_from_string(std::string_view str);
-seastar::sstring task_state_to_sstring(view_building_task::task_state state);
 
 } // namespace view_building
 
@@ -136,17 +114,11 @@ template <> struct fmt::formatter<db::view::view_building_task::task_type> : fmt
     }
 };
 
-template <> struct fmt::formatter<db::view::view_building_task::task_state> : fmt::formatter<string_view> {
-    auto format(db::view::view_building_task::task_state state, fmt::format_context& ctx) const {
-        return fmt::format_to(ctx.out(), "{}", db::view::task_state_to_sstring(state));
-    }
-};
-
 template <> struct fmt::formatter<db::view::view_building_task> : fmt::formatter<string_view> {
     auto format(db::view::view_building_task task, fmt::format_context& ctx) const {
         auto view_id = task.view_id ? fmt::to_string(*task.view_id) : "nullopt";
-        return fmt::format_to(ctx.out(), "view_building_task{{type: {}, state: {}, base_id: {}, view_id: {}, last_token: {}}}",
+        return fmt::format_to(ctx.out(), "view_building_task{{type: {}, aborted: {}, base_id: {}, view_id: {}, last_token: {}}}",
-                task.type, task.state, task.base_id, view_id, task.last_token);
+                task.type, task.aborted, task.base_id, view_id, task.last_token);
     }
 };
 
@@ -161,18 +133,3 @@ template <> struct fmt::formatter<db::view::replica_tasks> : fmt::formatter<stri
         return fmt::format_to(ctx.out(), "{{view_tasks: {}, staging_tasks: {}}}", replica_tasks.view_tasks, replica_tasks.staging_tasks);
     }
 };
-
-template <> struct fmt::formatter<db::view::view_task_result> : fmt::formatter<string_view> {
-    auto format(db::view::view_task_result result, fmt::format_context& ctx) const {
-        std::string_view res;
-        switch (result.status) {
-            case db::view::view_task_result::command_status::success:
-            res = "success";
-            break;
-        case db::view::view_task_result::command_status::abort:
-            res = "abort";
-            break;
-        }
-        return format_to(ctx.out(), "{}", res);
-    }
-};

db/view/view_building_task_mutation_builder.cc

@@ -25,8 +25,8 @@ view_building_task_mutation_builder& view_building_task_mutation_builder::set_ty
     _m.set_clustered_cell(get_ck(id), "type", data_value(task_type_to_sstring(type)), _ts);
     return *this;
 }
-view_building_task_mutation_builder& view_building_task_mutation_builder::set_state(utils::UUID id, db::view::view_building_task::task_state state) {
+view_building_task_mutation_builder& view_building_task_mutation_builder::set_aborted(utils::UUID id, bool aborted) {
-    _m.set_clustered_cell(get_ck(id), "state", data_value(task_state_to_sstring(state)), _ts);
+    _m.set_clustered_cell(get_ck(id), "aborted", data_value(aborted), _ts);
     return *this;
 }
 view_building_task_mutation_builder& view_building_task_mutation_builder::set_base_id(utils::UUID id, table_id base_id) {

db/view/view_building_task_mutation_builder.hh

@@ -32,7 +32,7 @@ public:
     static utils::UUID new_id();
 
     view_building_task_mutation_builder& set_type(utils::UUID id, db::view::view_building_task::task_type type);
-    view_building_task_mutation_builder& set_state(utils::UUID id, db::view::view_building_task::task_state state);
+    view_building_task_mutation_builder& set_aborted(utils::UUID id, bool aborted);
     view_building_task_mutation_builder& set_base_id(utils::UUID id, table_id base_id);
     view_building_task_mutation_builder& set_view_id(utils::UUID id, table_id view_id);
     view_building_task_mutation_builder& set_last_token(utils::UUID id, dht::token last_token);

db/view/view_building_worker.cc

@@ -22,6 +22,7 @@
 #include "replica/database.hh"
 #include "service/storage_proxy.hh"
 #include "service/raft/raft_group0_client.hh"
+#include "service/raft/raft_group0.hh"
 #include "schema/schema_fwd.hh"
 #include "idl/view.dist.hh"
 #include "sstables/sstables.hh"
@@ -114,11 +115,11 @@ static locator::tablet_id get_sstable_tablet_id(const locator::tablet_map& table
     return tablet_id;
 }
 
-view_building_worker::view_building_worker(replica::database& db, db::system_keyspace& sys_ks, service::migration_notifier& mnotifier, service::raft_group0_client& group0_client, view_update_generator& vug, netw::messaging_service& ms, view_building_state_machine& vbsm)
+view_building_worker::view_building_worker(replica::database& db, db::system_keyspace& sys_ks, service::migration_notifier& mnotifier, service::raft_group0& group0, view_update_generator& vug, netw::messaging_service& ms, view_building_state_machine& vbsm)
         : _db(db)
         , _sys_ks(sys_ks)
         , _mnotifier(mnotifier)
-        , _group0_client(group0_client)
+        , _group0(group0)
         , _vug(vug)
         , _messaging(ms)
         , _vb_state_machine(vbsm)
@@ -145,6 +146,7 @@ future<> view_building_worker::drain() {
     if (!_as.abort_requested()) {
         _as.request_abort();
     }
+    _state._mutex.broken();
     _staging_sstables_mutex.broken();
     _sstables_to_register_event.broken();
     if (this_shard_id() == 0) {
@@ -154,8 +156,7 @@ future<> view_building_worker::drain() {
         co_await std::move(state_observer);
         co_await _mnotifier.unregister_listener(this);
     }
-    co_await _state.clear_state();
+    co_await _state.clear();
-    _state.state_updated_cv.broken();
     co_await uninit_messaging_service();
 }
 
@@ -224,22 +225,22 @@ future<> view_building_worker::create_staging_sstable_tasks() {
 
     utils::chunked_vector<canonical_mutation> cmuts;
 
-    auto guard = co_await _group0_client.start_operation(_as);
+    auto guard = co_await _group0.client().start_operation(_as);
     auto my_host_id = _db.get_token_metadata().get_topology().my_host_id();
     for (auto& [table_id, sst_infos]: _sstables_to_register) {
         for (auto& sst_info: sst_infos) {
             view_building_task task {
-                utils::UUID_gen::get_time_UUID(), view_building_task::task_type::process_staging, view_building_task::task_state::idle,
+                utils::UUID_gen::get_time_UUID(), view_building_task::task_type::process_staging, false,
                 table_id, ::table_id{}, {my_host_id, sst_info.shard}, sst_info.last_token
             };
-            auto mut = co_await _group0_client.sys_ks().make_view_building_task_mutation(guard.write_timestamp(), task);
+            auto mut = co_await _group0.client().sys_ks().make_view_building_task_mutation(guard.write_timestamp(), task);
             cmuts.emplace_back(std::move(mut));
         }
     }
 
     vbw_logger.debug("Creating {} process_staging view_building_tasks", cmuts.size());
-    auto cmd = _group0_client.prepare_command(service::write_mutations{std::move(cmuts)}, guard, "create view building tasks");
+    auto cmd = _group0.client().prepare_command(service::write_mutations{std::move(cmuts)}, guard, "create view building tasks");
-    co_await _group0_client.add_entry(std::move(cmd), std::move(guard), _as);
+    co_await _group0.client().add_entry(std::move(cmd), std::move(guard), _as);
 
     // Move staging sstables from `_sstables_to_register` (on shard0) to `_staging_sstables` on corresponding shards.
     // Firstly reorgenize `_sstables_to_register` for easier movement.
@@ -340,22 +341,16 @@ future<> view_building_worker::run_view_building_state_observer() {
 
     while (!_as.abort_requested()) {
         bool sleep = false;
-        _state.some_batch_finished = false;
         try {
             vbw_logger.trace("view_building_state_observer() iteration");
-            auto read_apply_mutex_holder = co_await _group0_client.hold_read_apply_mutex(_as);
+            auto read_apply_mutex_holder = co_await _group0.client().hold_read_apply_mutex(_as);
 
             co_await update_built_views();
-            co_await update_building_state();
+            co_await check_for_aborted_tasks();
             _as.check();
 
             read_apply_mutex_holder.return_all();
-
-            // A batch could finished its work while the worker was
-            // updating the state. In that case we should do another iteration.
-            if (!_state.some_batch_finished) {
             co_await _vb_state_machine.event.wait();
-            }
         } catch (abort_requested_exception&) {
         } catch (broken_condition_variable&) {
         } catch (...) {
@@ -382,7 +377,7 @@ future<> view_building_worker::update_built_views() {
         auto schema = _db.find_schema(table_id);
         return std::make_pair(schema->ks_name(), schema->cf_name());
     };
-    auto& sys_ks = _group0_client.sys_ks();
+    auto& sys_ks = _group0.client().sys_ks();
 
     std::set<std::pair<sstring, sstring>> built_views;
     for (auto& [id, statuses]: _vb_state_machine.views_state.status_map) {
@@ -411,22 +406,35 @@ future<> view_building_worker::update_built_views() {
     }
 }
 
-future<> view_building_worker::update_building_state() {
+// Must be executed on shard0
-    co_await _state.update(*this);
+future<> view_building_worker::check_for_aborted_tasks() {
-    co_await _state.finish_completed_tasks();
+    return container().invoke_on_all([building_state = _vb_state_machine.building_state] (view_building_worker& vbw) -> future<> {
-    _state.state_updated_cv.broadcast();
+        auto lock = co_await get_units(vbw._state._mutex, 1, vbw._as);
-}
+        co_await vbw._state.update_processing_base_table(vbw._db, building_state, vbw._as);
+        if (!vbw._state._batch) {
+            co_return;
+        }
 
-bool view_building_worker::is_shard_free(shard_id shard) {
+        auto my_host_id = vbw._db.get_token_metadata().get_topology().my_host_id();
-    return !std::ranges::any_of(_state.tasks_map, [&shard] (auto& task_entry) {
+        auto my_replica = locator::tablet_replica{my_host_id, this_shard_id()};
-        return task_entry.second->replica.shard == shard && task_entry.second->state == view_building_worker::batch_state::in_progress;
+        auto tasks_map = vbw._state._batch->tasks; // Potentially, we'll remove elements from the map, so we need a copy to iterate over it
+        for (auto& [id, t]: tasks_map) {
+            auto task_opt = building_state.get_task(t.base_id, my_replica, id);
+            if (!task_opt || task_opt->get().aborted) {
+                co_await vbw._state._batch->abort_task(id);
+            }
+        }
+
+        if (vbw._state._batch->tasks.empty()) {
+            co_await vbw._state.clean_up_after_batch();
+        }
     });
 }
 
 void view_building_worker::init_messaging_service() {
-    ser::view_rpc_verbs::register_work_on_view_building_tasks(&_messaging, [this] (std::vector<utils::UUID> ids) -> future<std::vector<view_task_result>> {
+    ser::view_rpc_verbs::register_work_on_view_building_tasks(&_messaging, [this] (raft::term_t term, shard_id shard, std::vector<utils::UUID> ids) -> future<std::vector<utils::UUID>> {
-        return container().invoke_on(0, [ids = std::move(ids)] (view_building_worker& vbw) mutable -> future<std::vector<view_task_result>> {
+        return container().invoke_on(shard, [term, ids = std::move(ids)] (auto& vbw) mutable -> future<std::vector<utils::UUID>> {
-            return vbw.work_on_tasks(std::move(ids));
+            return vbw.work_on_tasks(term, std::move(ids));
         });
     });
 }
@@ -435,236 +443,53 @@ future<> view_building_worker::uninit_messaging_service() {
     return ser::view_rpc_verbs::unregister(&_messaging);
 }
 
-future<std::vector<view_task_result>> view_building_worker::work_on_tasks(std::vector<utils::UUID> ids) {
-    vbw_logger.debug("Got request for results of tasks: {}", ids);
-    auto guard = co_await _group0_client.start_operation(_as, service::raft_timeout{});
-    auto processing_base_table = _state.processing_base_table;
-
-    auto are_tasks_finished = [&] () {
-        return std::ranges::all_of(ids, [this] (const utils::UUID& id) {
-            return _state.finished_tasks.contains(id) || _state.aborted_tasks.contains(id);
-        });
-    };
-
-    auto get_results = [&] () -> std::vector<view_task_result> {
-        std::vector<view_task_result> results;
-        for (const auto& id: ids) {
-            if (_state.finished_tasks.contains(id)) {
-                results.emplace_back(view_task_result::command_status::success);
-            } else if (_state.aborted_tasks.contains(id)) {
-                results.emplace_back(view_task_result::command_status::abort);
-            } else {
-                // This means that the task was aborted. Throw an error,
-                // so the coordinator will refresh its state and retry without aborted IDs.
-                throw std::runtime_error(fmt::format("No status for task {}", id));
-            }
-        }
-        return results;
-    };
-
-    if (are_tasks_finished()) {
-        // If the batch is already finished, we can return the results immediately.
-        vbw_logger.debug("Batch with tasks {} is already finished, returning results", ids);
-        co_return get_results();
-    }
-
-    // All of the tasks should be executed in the same batch
-    // (their statuses are set to started in the same group0 operation).
-    // If any ID is not present in the `tasks_map`, it means that it was aborted and we should fail this RPC call,
-    // so the coordinator can retry without aborted IDs.
-    // That's why we can identify the batch by random (.front()) ID from the `ids` vector.
-    auto id = ids.front();
-    while (!_state.tasks_map.contains(id) && processing_base_table == _state.processing_base_table) {
-        vbw_logger.warn("Batch with task {} is not found in tasks map, waiting until worker updates its state", id);
-        service::release_guard(std::move(guard));
-        co_await _state.state_updated_cv.wait();
-        guard = co_await _group0_client.start_operation(_as, service::raft_timeout{});
-    }
-
-    if (processing_base_table != _state.processing_base_table) {
-        // If the processing base table was changed, we should fail this RPC call because the tasks were aborted.
-        throw std::runtime_error(fmt::format("Processing base table was changed to {} ", _state.processing_base_table));
-    }
-
-    // Validate that any of the IDs wasn't aborted.
-    for (const auto& tid: ids) {
-        if (!_state.tasks_map[id]->tasks.contains(tid)) {
-            vbw_logger.warn("Task {} is not found in the batch", tid);
-            throw std::runtime_error(fmt::format("Task {} is not found in the batch", tid));
-        }
-    }
-
-    if (_state.tasks_map[id]->state == view_building_worker::batch_state::idle) {
-        vbw_logger.debug("Starting batch with tasks {}", _state.tasks_map[id]->tasks);
-        if (!is_shard_free(_state.tasks_map[id]->replica.shard)) {
-            throw std::runtime_error(fmt::format("Tried to start view building tasks ({}) on shard {} but the shard is busy", _state.tasks_map[id]->tasks, _state.tasks_map[id]->replica.shard, _state.tasks_map[id]->tasks));
-        }
-        _state.tasks_map[id]->start();
-    }
-
-    service::release_guard(std::move(guard));
-    while (!_as.abort_requested()) {
-        auto read_apply_mutex_holder = co_await _group0_client.hold_read_apply_mutex(_as);
-
-        if (are_tasks_finished()) {
-            co_return get_results();
-        }
-
-        // Check if the batch is still alive
-        if (!_state.tasks_map.contains(id)) {
-            throw std::runtime_error(fmt::format("Batch with task {} is not found in tasks map anymore.", id));
-        }
-
-        read_apply_mutex_holder.return_all();
-        co_await _state.tasks_map[id]->batch_done_cv.wait();
-    }
-    throw std::runtime_error("View building worker was aborted");
-}
-
-// Validates if the task can be executed in a batch on the same shard.
-static bool validate_can_be_one_batch(const view_building_task& t1, const view_building_task& t2) {
-    return t1.type == t2.type && t1.base_id == t2.base_id && t1.replica == t2.replica && t1.last_token == t2.last_token;
-}
-
 static std::unordered_set<table_id> get_ids_of_all_views(replica::database& db, table_id table_id) {
     return db.find_column_family(table_id).views() | std::views::transform([] (view_ptr vptr) {
         return vptr->id();
     }) | std::ranges::to<std::unordered_set>();;
 }
 
-future<> view_building_worker::local_state::flush_table(view_building_worker& vbw, table_id table_id) {
+// If `state::processing_base_table` is diffrent that the `view_building_state::currently_processed_base_table`,
-    // `table_id` should point to currently processing base table but
+// clear the state, save and flush new base table
-    // `view_building_worker::local_state::processing_base_table` may not be set to it yet, 
+future<> view_building_worker::state::update_processing_base_table(replica::database& db, const view_building_state& building_state, abort_source& as) {
-    // so we need to pass it directly
+    if (processing_base_table != building_state.currently_processed_base_table) {
-    co_await vbw.container().invoke_on_all([table_id] (view_building_worker& local_vbw) -> future<> {
+        co_await clear();
-        auto base_cf = local_vbw._db.find_column_family(table_id).shared_from_this();
+        if (building_state.currently_processed_base_table) {
-        co_await when_all(base_cf->await_pending_writes(), base_cf->await_pending_streams());
+            co_await flush_base_table(db, *building_state.currently_processed_base_table, as);
-        co_await flush_base(base_cf, local_vbw._as);
-    });
-
-    flushed_views = get_ids_of_all_views(vbw._db, table_id);
-}
-
-future<> view_building_worker::local_state::update(view_building_worker& vbw) {
-    const auto& vb_state = vbw._vb_state_machine.building_state;
-
-    // Check if the base table to process was changed.
-    // If so, we clear the state, aborting tasks for previous base table and starting new ones for the new base table.
-    if (processing_base_table != vb_state.currently_processed_base_table) {
-        co_await clear_state();
-
-        if (vb_state.currently_processed_base_table) {
-            // When we start to process new base table, we need to flush its current data, so we can build the view.
-            co_await flush_table(vbw, *vb_state.currently_processed_base_table);
-        }
-
-        processing_base_table = vb_state.currently_processed_base_table;
-        vbw_logger.info("Processing base table was changed to: {}", processing_base_table);
-    }
-
-    if (!processing_base_table) {
-        vbw_logger.debug("No base table is selected to be processed.");
-        co_return;
-    }
-
-    std::vector<table_id> new_views;
-    auto all_view_ids = get_ids_of_all_views(vbw._db, *processing_base_table);
-    std::ranges::set_difference(all_view_ids, flushed_views, std::back_inserter(new_views));
-    if (!new_views.empty()) {
-        // Flush base table again in any new view was created, so the view building tasks will see up-to-date sstables.
-        // Otherwise, we may lose mutations created after previous flush but before the new view was created.
-        co_await flush_table(vbw, *processing_base_table);
-    }
-
-    auto erm = vbw._db.find_column_family(*processing_base_table).get_effective_replication_map();
-    auto my_host_id = erm->get_topology().my_host_id();
-    auto current_tasks_for_this_host = vb_state.get_tasks_for_host(*processing_base_table, my_host_id);
-
-    // scan view building state, collect alive and new (in STARTED state but not started by this worker) tasks
-    std::unordered_map<shard_id, std::vector<view_building_task>> new_tasks;
-    std::unordered_set<utils::UUID> alive_tasks; // save information about alive tasks to cleanup done/aborted ones
-    for (auto& task_ref: current_tasks_for_this_host) {
-        auto& task = task_ref.get();
-        auto id = task.id;
-
-        if (task.state != view_building_task::task_state::aborted) {
-            alive_tasks.insert(id);
-        }
-
-        if (tasks_map.contains(id) || finished_tasks.contains(id)) {
-            continue;
-        }
-        else if (task.state == view_building_task::task_state::started) {
-            auto shard = task.replica.shard;
-            if (new_tasks.contains(shard) && !validate_can_be_one_batch(new_tasks[shard].front(), task)) {
-                // Currently we allow only one batch per shard at a time
-                on_internal_error(vbw_logger, fmt::format("Got not-compatible tasks for the same shard. Task: {}, other: {}", new_tasks[shard].front(), task));
-            }
-            new_tasks[shard].push_back(task);
-        }
-        co_await coroutine::maybe_yield();
-    }
-
-    auto tasks_map_copy = tasks_map;
-
-    // Clear aborted tasks from tasks_map
-    for (auto it = tasks_map_copy.begin(); it != tasks_map_copy.end();) {
-        if (!alive_tasks.contains(it->first)) {
-            vbw_logger.debug("Aborting task {}", it->first);
-            aborted_tasks.insert(it->first);
-            co_await it->second->abort_task(it->first);
-            it = tasks_map_copy.erase(it);
-        } else {
-            ++it;
-        }
-    }
-
-    // Create batches for new tasks
-    for (const auto& [shard, shard_tasks]: new_tasks) {
-        auto tasks = shard_tasks | std::views::transform([] (const view_building_task& t) {
-            return std::make_pair(t.id, t);
-        }) | std::ranges::to<std::unordered_map>();
-        auto batch = seastar::make_shared<view_building_worker::batch>(vbw.container(), tasks, shard_tasks.front().base_id, shard_tasks.front().replica);
-
-        for (auto& [id, _]: tasks) {
-            tasks_map_copy.insert({id, batch});
-        }
-        co_await coroutine::maybe_yield();
-    }
-
-    tasks_map = std::move(tasks_map_copy);
-}
-
-future<> view_building_worker::local_state::finish_completed_tasks() {
-    for (auto it = tasks_map.begin(); it != tasks_map.end();) {
-        if (it->second->state == view_building_worker::batch_state::idle) {
-            ++it;
-        } else if (it->second->state == view_building_worker::batch_state::in_progress) {
-            vbw_logger.debug("Task {} is still in progress", it->first);
-            ++it;
-        } else {
-            co_await it->second->work.get_future();
-            finished_tasks.insert(it->first);
-            vbw_logger.info("Task {} was completed", it->first);
-            it->second->batch_done_cv.broadcast();
-            it = tasks_map.erase(it);
         }
+        processing_base_table = building_state.currently_processed_base_table;
     }
 }
 
-future<> view_building_worker::local_state::clear_state() {
+// If `_batch` ptr points to valid object, co_await its `work` future, save completed tasks and delete the object
-    for (auto& [_, batch]: tasks_map) {
+future<> view_building_worker::state::clean_up_after_batch() {
-        co_await batch->abort();
+    if (_batch) {
+        co_await std::move(_batch->work);
+        for (auto& [id, _]: _batch->tasks) {
+            completed_tasks.insert(id);
         }
+        _batch = nullptr;
+    }
+}
 
+// Flush base table, set is as currently processing base table and save which views exist at the time of flush
+future<> view_building_worker::state::flush_base_table(replica::database& db, table_id base_table_id, abort_source& as) {
+    auto cf = db.find_column_family(base_table_id).shared_from_this();
+    co_await when_all(cf->await_pending_writes(), cf->await_pending_streams());
+    co_await flush_base(cf, as);
+    processing_base_table = base_table_id;
+    flushed_views = get_ids_of_all_views(db, base_table_id);
+}
+
+future<> view_building_worker::state::clear() {
+    if (_batch) {
+        _batch->as.request_abort();
+        co_await std::move(_batch->work);
+        _batch = nullptr;
+    }
     processing_base_table.reset();
+    completed_tasks.clear();
     flushed_views.clear();
-    tasks_map.clear();
-    finished_tasks.clear();
-    aborted_tasks.clear();
-    state_updated_cv.broadcast();
-    some_batch_finished = false;
-    vbw_logger.debug("View building worker state was cleared.");
 }
 
 view_building_worker::batch::batch(sharded<view_building_worker>& vbw, std::unordered_map<utils::UUID, view_building_task> tasks, table_id base_id, locator::tablet_replica replica)
@@ -674,17 +499,12 @@ view_building_worker::batch::batch(sharded<view_building_worker>& vbw, std::unor
     , _vbw(vbw) {}
 
 void view_building_worker::batch::start() {
-    if (this_shard_id() != 0) {
+    if (this_shard_id() != replica.shard) {
-        on_internal_error(vbw_logger, "view_building_worker::batch should be started on shard0");
+        on_internal_error(vbw_logger, "view_building_worker::batch should be started on replica shard");
     }
 
-    state = batch_state::in_progress;
+    work = do_work().finally([this] {
-    work = smp::submit_to(replica.shard, [this] () -> future<> {
+        promise.set_value();
-        return do_work();
-    }).finally([this] () {
-        state = batch_state::finished;
-        _vbw.local()._state.some_batch_finished = true;
-        _vbw.local()._vb_state_machine.event.broadcast();
     });
 }
 
@@ -699,10 +519,6 @@ future<> view_building_worker::batch::abort() {
     co_await smp::submit_to(replica.shard, [this] () {
         as.request_abort();
     });
-
-    if (work.valid()) {
-        co_await work.get_future();
-    }
 }
 
 future<> view_building_worker::batch::do_work() {
@@ -896,6 +712,124 @@ void view_building_worker::cleanup_staging_sstables(locator::effective_replicati
     _staging_sstables[table_id].erase(first, last);
 }
 
+future<view_building_state> view_building_worker::get_latest_view_building_state(raft::term_t term) {
+    return smp::submit_to(0, [&sharded_vbw = container(), term] () -> future<view_building_state> {
+        auto& vbw = sharded_vbw.local();
+        // auto guard = vbw._group0.client().start_operation(vbw._as);
+
+        auto& raft_server = vbw._group0.group0_server();
+        auto group0_holder = vbw._group0.hold_group0_gate();
+        co_await raft_server.read_barrier(&vbw._as);
+        if (raft_server.get_current_term() != term) {
+           throw std::runtime_error(fmt::format("Invalid raft term. Got {} but current term is {}", term, raft_server.get_current_term()));
+        }
+
+        co_return vbw._vb_state_machine.building_state;
+    });
+}
+
+future<std::vector<utils::UUID>> view_building_worker::work_on_tasks(raft::term_t term, std::vector<utils::UUID> ids) {
+    auto collect_completed_tasks = [&] {
+        std::vector<utils::UUID> completed;
+        for (auto& id: ids) {
+            if (_state.completed_tasks.contains(id)) {
+                completed.push_back(id);
+            }
+        }
+        return completed;
+    };
+
+    auto lock = co_await get_units(_state._mutex, 1, _as);
+    // Firstly check if there is any batch that is finished but wasn't cleaned up.
+    if (_state._batch && _state._batch->promise.available()) {
+        co_await _state.clean_up_after_batch();
+    }
+
+    // Check if tasks were already completed.
+    // If only part of the tasks were finished, return the subset and don't execute the remaining tasks.
+    std::vector<utils::UUID> completed = collect_completed_tasks();
+    if (!completed.empty()) {
+        co_return completed;
+    }
+    lock.return_all();
+
+    auto building_state = co_await get_latest_view_building_state(term);
+
+    lock = co_await get_units(_state._mutex, 1, _as);
+    co_await _state.update_processing_base_table(_db, building_state, _as);
+    // If there is no running batch, create it.
+    if (!_state._batch) {
+        if (!_state.processing_base_table) {
+            throw std::runtime_error("view_building_worker::state::processing_base_table needs to be set to work on view building");
+        }
+
+        auto my_host_id = _db.get_token_metadata().get_topology().my_host_id();
+        auto my_replica = locator::tablet_replica{my_host_id, this_shard_id()};
+        std::unordered_map<utils::UUID, view_building_task> tasks;
+        for (auto& id: ids) {
+            auto task_opt = building_state.get_task(*_state.processing_base_table, my_replica, id);
+            if (!task_opt) {
+                throw std::runtime_error(fmt::format("Task {} was not found for base table {} on replica {}", id, *building_state.currently_processed_base_table, my_replica));
+            }
+            tasks.insert({id, *task_opt});
+        }
+#ifdef SEASTAR_DEBUG
+        auto& some_task = tasks.begin()->second;
+        for (auto& [_, t]: tasks) {
+            SCYLLA_ASSERT(t.base_id == some_task.base_id);
+            SCYLLA_ASSERT(t.last_token == some_task.last_token);
+            SCYLLA_ASSERT(t.replica == some_task.replica);
+            SCYLLA_ASSERT(t.type == some_task.type);
+            SCYLLA_ASSERT(t.replica.shard == this_shard_id());
+        }
+#endif
+
+        // If any view was added after we did the initial flush, we need to do it again
+        if (std::ranges::any_of(tasks | std::views::values, [&] (const view_building_task& t) {
+            return t.view_id && !_state.flushed_views.contains(*t.view_id);
+        })) {
+            co_await _state.flush_base_table(_db, *_state.processing_base_table, _as);
+        }
+
+        // Create and start the batch
+        _state._batch = std::make_unique<batch>(container(), std::move(tasks), *building_state.currently_processed_base_table, my_replica);
+        _state._batch->start();
+    }
+
+    if (std::ranges::all_of(ids, [&] (auto& id) { return !_state._batch->tasks.contains(id); })) {
+        throw std::runtime_error(fmt::format(
+                "None of the tasks requested to work on is executed in current view building batch. Batch executes: {}, the RPC requested: {}",
+                _state._batch->tasks | std::views::keys, ids));
+    }
+    auto batch_future = _state._batch->promise.get_shared_future();
+    lock.return_all();
+
+    co_await std::move(batch_future);
+
+    lock = co_await get_units(_state._mutex, 1, _as);
+    co_await _state.clean_up_after_batch();
+    co_return collect_completed_tasks();
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
 }
 
 }

db/view/view_building_worker.hh

@@ -16,6 +16,7 @@
 #include <unordered_set>
 #include "locator/abstract_replication_strategy.hh"
 #include "locator/tablets.hh"
+#include "raft/raft.hh"
 #include "seastar/core/gate.hh"
 #include "db/view/view_building_state.hh"
 #include "sstables/shared_sstable.hh"
@@ -31,7 +32,7 @@ class messaging_service;
 }
 
 namespace service {
-class raft_group0_client;
+class raft_group0;
 }
 
 namespace db {
@@ -65,27 +66,16 @@ class view_building_worker : public seastar::peering_sharded_service<view_buildi
      *
      * When `work` future is finished, it means all tasks in `tasks_ids` are done.
      *
-     * The batch lives on shard 0 exclusively.
+     * The batch lives on shard, where its executing its work exclusively.
-     * When the batch starts to execute its tasks, it firstly copies all necessary data
-     * to the designated shard, then the work is done on the local copy of the data only.
      */
-
-    enum class batch_state {
-        idle,
-        in_progress,
-        finished,
-    };
-
     class batch {
     public:
-        batch_state state = batch_state::idle;
         table_id base_id;
         locator::tablet_replica replica;
         std::unordered_map<utils::UUID, view_building_task> tasks;
 
-        shared_future<> work;
+        shared_promise<> promise;
-        condition_variable batch_done_cv;
+        future<> work = make_ready_future();
-        // The abort has to be used only on `replica.shard`
         abort_source as;
 
         batch(sharded<view_building_worker>& vbw, std::unordered_map<utils::UUID, view_building_task> tasks, table_id base_id, locator::tablet_replica replica);
@@ -101,35 +91,18 @@ class view_building_worker : public seastar::peering_sharded_service<view_buildi
 
     friend class batch;
 
-    struct local_state {
+    struct state {
         std::optional<table_id> processing_base_table = std::nullopt;
-        // Stores ids of views for which the flush was done.
+        std::unordered_set<utils::UUID> completed_tasks;
-        // When a new view is created, we need to flush the base table again,
+        std::unique_ptr<batch> _batch = nullptr;
-        // as data might be inserted.
         std::unordered_set<table_id> flushed_views;
-        std::unordered_map<utils::UUID, shared_ptr<batch>> tasks_map;
 
-        std::unordered_set<utils::UUID> finished_tasks;
+        semaphore _mutex = semaphore(1);
-        std::unordered_set<utils::UUID> aborted_tasks;
+        // All of the methods below should be executed while holding `_mutex` unit!
-
+        future<> update_processing_base_table(replica::database& db, const view_building_state& building_state, abort_source& as);
-        bool some_batch_finished = false;
+        future<> flush_base_table(replica::database& db, table_id base_table_id, abort_source& as);
-        condition_variable state_updated_cv;
+        future<> clean_up_after_batch();
-
+        future<> clear();
-        // Clears completed/aborted tasks and creates batches (without starting them) for started tasks.
-        // Returns a map of tasks per shard to execute.
-        future<> update(view_building_worker& vbw);
-
-        future<> finish_completed_tasks();
-
-        // The state can be aborted if, for example, a view is dropped, then all its tasks
-        // are aborted and the coordinator may choose new base table to process.
-        // This method aborts all batches as we stop to processing the current base table.
-        future<> clear_state();
-
-        // Flush table with `table_id` on all shards.
-        // This method should be used only on currently processing base table and
-        // it updates `flushed_views` field.
-        future<> flush_table(view_building_worker& vbw, table_id table_id);
     };
 
     // Wrapper which represents information needed to create
@@ -147,14 +120,14 @@ private:
     replica::database& _db;
     db::system_keyspace& _sys_ks;
     service::migration_notifier& _mnotifier;
-    service::raft_group0_client& _group0_client;
+    service::raft_group0& _group0;
     view_update_generator& _vug;
     netw::messaging_service& _messaging;
     view_building_state_machine& _vb_state_machine;
     abort_source _as;
     named_gate _gate;
 
-    local_state _state;
+    state _state;
     std::unordered_set<table_id> _views_in_progress;
     future<> _view_building_state_observer = make_ready_future<>();
 
@@ -166,7 +139,7 @@ private:
 
 public:
     view_building_worker(replica::database& db, db::system_keyspace& sys_ks, service::migration_notifier& mnotifier,
-            service::raft_group0_client& group0_client, view_update_generator& vug, netw::messaging_service& ms,
+            service::raft_group0& group0, view_update_generator& vug, netw::messaging_service& ms,
             view_building_state_machine& vbsm);
     future<> init();
 
@@ -185,10 +158,11 @@ public:
     void cleanup_staging_sstables(locator::effective_replication_map_ptr erm, table_id table_id, locator::tablet_id tid);
 
 private:
+    future<view_building_state> get_latest_view_building_state(raft::term_t term);
+    future<> check_for_aborted_tasks();
+
     future<> run_view_building_state_observer();
     future<> update_built_views();
-    future<> update_building_state();
-    bool is_shard_free(shard_id shard);
 
     dht::token_range get_tablet_token_range(table_id table_id, dht::token last_token);
     future<> do_build_range(table_id base_id, std::vector<table_id> views_ids, dht::token last_token, abort_source& as);
@@ -202,7 +176,7 @@ private:
 
     void init_messaging_service();
     future<> uninit_messaging_service();
-    future<std::vector<view_task_result>> work_on_tasks(std::vector<utils::UUID> ids);
+    future<std::vector<utils::UUID>> work_on_tasks(raft::term_t term, std::vector<utils::UUID> ids);
 };
 
 }

db/virtual_tables.cc

@@ -483,7 +483,7 @@ public:
         });
         co_await add_partition(mutation_sink, "load", [this] () -> future<sstring> {
             return map_reduce_tables<int64_t>([] (replica::table& tbl) {
-                return tbl.get_stats().live_disk_space_used;
+                return tbl.get_stats().live_disk_space_used.on_disk;
             }).then([] (int64_t load) {
                 return format("{}", load);
             });
@@ -1158,6 +1158,104 @@ private:
     }
 };
 
+class tablet_sizes : public group0_virtual_table {
+private:
+    sharded<service::tablet_allocator>& _talloc;
+    sharded<replica::database>& _db;
+public:
+    tablet_sizes(sharded<service::tablet_allocator>& talloc,
+                 sharded<replica::database>& db,
+                 sharded<service::raft_group_registry>& raft_gr,
+                 sharded<netw::messaging_service>& ms)
+        : group0_virtual_table(build_schema(), raft_gr, ms)
+        , _talloc(talloc)
+        , _db(db)
+    { }
+
+    future<> execute_on_leader(std::function<void(mutation)> mutation_sink, reader_permit permit) override {
+        auto stats = _talloc.local().get_load_stats();
+        while (!stats) {
+            // Wait for stats to be refreshed by topology coordinator
+            {
+                abort_on_expiry aoe(permit.timeout());
+                reader_permit::awaits_guard ag(permit);
+                co_await seastar::sleep_abortable(std::chrono::milliseconds(200), aoe.abort_source());
+            }
+            if (!co_await is_leader(permit)) {
+                co_await redirect_to_leader(std::move(mutation_sink), std::move(permit));
+                co_return;
+            }
+            stats = _talloc.local().get_load_stats();
+        }
+
+        auto tm = _db.local().get_token_metadata_ptr();
+
+        auto prepare_replica_sizes = [] (const std::unordered_map<host_id, uint64_t>& replica_sizes) {
+            map_type_impl::native_type tmp;
+            for (auto& r: replica_sizes) {
+                auto replica = r.first.uuid();
+                int64_t tablet_size = int64_t(r.second);
+                auto map_element = std::make_pair<data_value, data_value>(data_value(replica), data_value(tablet_size));
+                tmp.push_back(std::move(map_element));
+            }
+            return tmp;
+        };
+
+        auto prepare_missing_replica = [] (const std::unordered_set<host_id>& missing_replicas) {
+            set_type_impl::native_type tmp;
+            for (auto& r: missing_replicas) {
+                tmp.push_back(data_value(r.uuid()));
+            }
+            return tmp;
+        };
+
+        auto map_type = map_type_impl::get_instance(uuid_type, long_type, false);
+        auto set_type = set_type_impl::get_instance(uuid_type, false);
+        for (auto&& [table, tmap] : tm->tablets().all_tables_ungrouped()) {
+            mutation m(schema(), make_partition_key(table));
+            co_await tmap->for_each_tablet([&] (locator::tablet_id tid, const locator::tablet_info& tinfo) -> future<> {
+                auto trange = tmap->get_token_range(tid);
+                int64_t last_token = trange.end()->value().raw();
+                auto& r = m.partition().clustered_row(*schema(), clustering_key::from_single_value(*schema(), data_value(last_token).serialize_nonnull()));
+                const range_based_tablet_id rb_tid {table, trange};
+                std::unordered_map<host_id, uint64_t> replica_sizes;
+                std::unordered_set<host_id> missing_replicas;
+                for (auto& replica : tinfo.replicas) {
+                    auto tablet_size_opt = stats->get_tablet_size(replica.host, rb_tid);
+                    if (tablet_size_opt) {
+                        replica_sizes[replica.host] = *tablet_size_opt;
+                    } else {
+                        missing_replicas.insert(replica.host);
+                    }
+                }
+                set_cell(r.cells(), "replicas", make_map_value(map_type, prepare_replica_sizes(replica_sizes)));
+                set_cell(r.cells(), "missing_replicas", make_set_value(set_type, prepare_missing_replica(missing_replicas)));
+                return make_ready_future<>();
+            });
+
+            mutation_sink(m);
+        }
+    }
+
+private:
+    static schema_ptr build_schema() {
+        auto id = generate_legacy_id(system_keyspace::NAME, "tablet_sizes");
+        return schema_builder(system_keyspace::NAME, "tablet_sizes", std::make_optional(id))
+            .with_column("table_id", uuid_type, column_kind::partition_key)
+            .with_column("last_token", long_type, column_kind::clustering_key)
+            .with_column("replicas", map_type_impl::get_instance(uuid_type, long_type, false))
+            .with_column("missing_replicas", set_type_impl::get_instance(uuid_type, false))
+            .with_sharder(1, 0) // shard0-only
+            .with_hash_version()
+            .build();
+    }
+
+    dht::decorated_key make_partition_key(table_id table) {
+        return dht::decorate_key(*_s, partition_key::from_single_value(
+                *_s, data_value(table.uuid()).serialize_nonnull()));
+    }
+};
+
 class cdc_timestamps_table : public streaming_virtual_table {
 private:
     replica::database& _db;
@@ -1353,6 +1451,7 @@ future<> initialize_virtual_tables(
     co_await add_table(std::make_unique<clients_table>(ss));
     co_await add_table(std::make_unique<raft_state_table>(dist_raft_gr));
     co_await add_table(std::make_unique<load_per_node>(tablet_allocator, dist_db, dist_raft_gr, ms, dist_gossiper));
+    co_await add_table(std::make_unique<tablet_sizes>(tablet_allocator, dist_db, dist_raft_gr, ms));
     co_await add_table(std::make_unique<cdc_timestamps_table>(db, ss));
     co_await add_table(std::make_unique<cdc_streams_table>(db, ss));
 

dht/CMakeLists.txt

@@ -18,6 +18,9 @@ target_link_libraries(scylla_dht
   PRIVATE
     replica)
 
+if (Scylla_USE_PRECOMPILED_HEADER_USE)
+  target_precompile_headers(scylla_dht REUSE_FROM scylla-precompiled-header)
+endif()
 add_whole_archive(dht scylla_dht)
 
 check_headers(check-headers scylla_dht

dist/common/systemd/scylla-server.slice

@@ -6,13 +6,7 @@ Before=slices.target
 MemoryAccounting=true
 IOAccounting=true
 CPUAccounting=true
-# Systemd deprecated settings BlockIOWeight and CPUShares. But they are still the ones used in RHEL7
-# Newer SystemD wants IOWeight and CPUWeight instead. Luckily both newer and older SystemD seem to
-# ignore the unwanted option so safest to get both. Using just the old versions would work too but
-# seems less future proof. Using just the new versions does not work at all for RHEL7/
-BlockIOWeight=1000
 IOWeight=1000
 MemorySwapMax=0
-CPUShares=1000
 CPUWeight=1000
 

dist/debian/debian/scylla-server.install

@@ -2,7 +2,6 @@ etc/default/scylla-server
 etc/default/scylla-housekeeping
 etc/scylla.d/*.conf
 etc/bash_completion.d/nodetool-completion
-opt/scylladb/share/p11-kit/modules/*
 opt/scylladb/share/doc/scylla/*
 opt/scylladb/share/doc/scylla/licenses/
 usr/lib/systemd/system/*.timer

dist/redhat/scylla.spec

@@ -122,7 +122,6 @@ ln -sfT /etc/scylla /var/lib/scylla/conf
 %config(noreplace) %{_sysconfdir}/sysconfig/scylla-housekeeping
 %attr(0755,root,root) %dir %{_sysconfdir}/scylla.d
 %config(noreplace) %{_sysconfdir}/scylla.d/*.conf
-/opt/scylladb/share/p11-kit/modules/*
 /opt/scylladb/share/doc/scylla/*
 %{_unitdir}/scylla-fstrim.service
 %{_unitdir}/scylla-housekeeping-daily.service

docs/README-metrics.md

@@ -0,0 +1,65 @@
+# ScyllaDB metrics docs scripts
+
+The following files extracts metrics from C++ source files and generates documentation:
+
+- **`scripts/get_description.py`** - Metrics parser and extractor
+- **`scripts/metrics-config.yml`** - Configuration for special cases only
+- **`docs/_ext/scylladb_metrics.py`** - Sphinx extension for rendering
+
+## Configuration
+
+The system automatically handles most metrics extraction. You only need configuration in the `metrics-config.yml` file for:
+
+**Complex parameter combinations:**
+```yaml
+"cdc/log.cc":
+  params:
+    part_name;suffix: [["static_row", "total"], ["clustering_row", "failed"]]
+    kind: ["total", "failed"]
+```
+
+**Multiple parameter values:**
+```yaml
+"service/storage_proxy.cc":
+  params:
+    _short_description_prefix: ["total_write_attempts", "write_errors"]
+```
+
+**Complex expressions:**
+```yaml
+"tracing/tracing.cc":
+  params:
+    "max_pending_trace_records + write_event_records_threshold": "max_pending_trace_records + write_event_records_threshold"
+```
+
+**Group assignments:**
+```yaml
+"cql3/query_processor.cc":
+  groups:
+    "80": query_processor
+```
+
+**Skip files:**
+```yaml
+"seastar/tests/unit/metrics_test.cc": skip
+```
+
+## Validation
+
+Use the built-in validation to check all metrics files:
+
+```bash
+# Validate all metrics files
+python scripts/get_description.py --validate -c scripts/metrics-config.yml
+
+# Validate with verbose output
+python scripts/get_description.py --validate -c scripts/metrics-config.yml -v
+```
+
+The GitHub workflow `docs-validate-metrics.yml` automatically runs validation on PRs to `master` that modify `.cc` files or metrics configuration.
+
+## Common fixes
+
+- **"Parameter not found"**: Add parameter mapping to config `params` section
+- **"Could not resolve param"**: Check parameter name matches C++ code exactly
+- **"No group found"**: Add group mapping or verify `add_group()` calls

docs/_ext/scylladb_metrics.py

@@ -27,38 +27,48 @@ class MetricsProcessor:
         os.makedirs(output_directory, exist_ok=True)
         return output_directory
 
-    def _process_single_file(self, file_path, destination_path, metrics_config_path):
+    def _process_single_file(self, file_path, destination_path, metrics_config_path, strict=False):
         with open(file_path, 'r', encoding='utf-8') as f:
             content = f.read()
         if self.MARKER in content and not os.path.exists(destination_path):
             try:
-                metrics_file = metrics.get_metrics_from_file(file_path, "scylla", metrics.get_metrics_information(metrics_config_path))
+                metrics_info = metrics.get_metrics_information(metrics_config_path)
+                # Get relative path to the repo root
+                relative_path = os.path.relpath(file_path, os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
+                repo_root = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+                old_cwd = os.getcwd()
+                os.chdir(repo_root)
+                # Get metrics from the file
+                try:
+                    metrics_file = metrics.get_metrics_from_file(relative_path, "scylla_", metrics_info, strict=strict)
+                finally:
+                    os.chdir(old_cwd)
+                if metrics_file:
                     with open(destination_path, 'w+', encoding='utf-8') as f:
                         json.dump(metrics_file, f, indent=4)
-            except SystemExit:
+                    LOGGER.info(f'Generated {len(metrics_file)} metrics for {file_path}')
-                LOGGER.info(f'Skipping file: {file_path}')
+                else:
+                    LOGGER.info(f'No metrics generated for {file_path}')
             except Exception as error:
-                # Remove [Errno X] prefix from error message
+                LOGGER.info(f'Error processing {file_path}: {str(error)}')
-                error_msg = str(error)
-                if '[Errno' in error_msg:
-                    error_msg = error_msg.split('] ', 1)[1]
-                LOGGER.info(error_msg)
 
-    def _process_metrics_files(self, repo_dir, output_directory, metrics_config_path):
+    def _process_metrics_files(self, repo_dir, output_directory, metrics_config_path, strict=False):
         for root, _, files in os.walk(repo_dir):
             for file in files:
                 if file.endswith(".cc"):
                     file_path = os.path.join(root, file)
                     file_name = os.path.splitext(file)[0] + ".json"
                     destination_path = os.path.join(output_directory, file_name)
-                    self._process_single_file(file_path, destination_path, metrics_config_path)
+                    self._process_single_file(file_path, destination_path, metrics_config_path, strict)
 
     def run(self, app, exception=None):
         repo_dir = os.path.abspath(os.path.join(app.srcdir, ".."))
         metrics_config_path = os.path.join(repo_dir, app.config.scylladb_metrics_config_path)
         output_directory = self._create_output_directory(app, app.config.scylladb_metrics_directory)
 
-        self._process_metrics_files(repo_dir, output_directory, metrics_config_path)
+        strict_mode = getattr(app.config, 'scylladb_metrics_strict_mode', False) or False
+
+        self._process_metrics_files(repo_dir, output_directory, metrics_config_path, strict_mode)
 
 
 class MetricsTemplateDirective(DataTemplateJSON):
@@ -163,7 +173,7 @@ class MetricsDirective(Directive):
         output = []
         try:
             relative_path_from_current_rst = self._get_relative_path(metrics_directory, app, docname)
-            files = os.listdir(metrics_directory)
+            files = sorted(os.listdir(metrics_directory))
             for _, file in enumerate(files):
                 output.extend(self._process_file(file, relative_path_from_current_rst))
         except Exception as error:
@@ -174,6 +184,7 @@ def setup(app):
     app.add_config_value("scylladb_metrics_directory", default="_data/metrics", rebuild="html")
     app.add_config_value("scylladb_metrics_config_path", default='scripts/metrics-config.yml', rebuild="html")
     app.add_config_value('scylladb_metrics_option_template', default='metrics_option.tmpl', rebuild='html', types=[str])
+    app.add_config_value('scylladb_metrics_strict_mode', default=None, rebuild='html', types=[bool])
     app.connect("builder-inited", MetricsProcessor().run)
     app.add_object_type(
         'metrics_option',

docs/_ext/utils.py

@@ -29,6 +29,7 @@ def readable_desc_rst(description):
 
         cleaned_line = cleaned_line.lstrip()
         cleaned_line = cleaned_line.replace('"', '')
+        cleaned_line = cleaned_line.replace('`', '\\`')
         
         if cleaned_line != '':
             cleaned_line = indent + cleaned_line

docs/_utils/redirects.yaml

@@ -1,6 +1,18 @@
 ### a dictionary of redirections
 #old path: new path
 
+# Move the diver information to another project
+
+/stable/using-scylla/drivers/index.html: https://docs.scylladb.com/stable/drivers/index.html
+/stable/using-scylla/drivers/dynamo-drivers/index.html: https://docs.scylladb.com/stable/drivers/dynamo-drivers.html
+/stable/using-scylla/drivers/cql-drivers/index.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+/stable/using-scylla/drivers/cql-drivers/scylla-python-driver.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+/stable/using-scylla/drivers/cql-drivers/scylla-java-driver.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+/stable/using-scylla/drivers/cql-drivers/scylla-go-driver.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+/stable/using-scylla/drivers/cql-drivers/scylla-gocqlx-driver.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+/stable/using-scylla/drivers/cql-drivers/scylla-cpp-driver.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+/stable/using-scylla/drivers/cql-drivers/scylla-rust-driver.html: https://docs.scylladb.com/stable/drivers/cql-drivers.html
+
 # Redirect 2025.1 upgrade guides that are not on master but were indexed by Google (404 reported)
 
 /master/upgrade/upgrade-guides/upgrade-guide-from-2024.x-to-2025.1/upgrade-guide-from-2024.x-to-2025.1.html: https://docs.scylladb.com/manual/stable/upgrade/index.html

docs/alternator/compatibility.md

@@ -428,3 +428,7 @@ they should be easy to detect. Here is a list of these unimplemented features:
   that can be used to achieve consistent reads on global (multi-region) tables.
   This table option was added as a preview to DynamoDB in December 2024.
   <https://github.com/scylladb/scylladb/issues/21852>
+
+* Alternator does not support multi-attribute (composite) keys in GSIs.
+  This feature was added to DynamoDB in November 2025.
+  <https://github.com/scylladb/scylladb/issues/27182>

docs/conf.py

@@ -76,7 +76,7 @@ author = u"ScyllaDB Project Contributors"
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store', 'lib', 'lib64','**/_common/*', 'README.md', 'index.md', '.git', '.github', '_utils', 'rst_include', 'venv', 'dev', '_data/**']
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store', 'lib', 'lib64','**/_common/*', 'README.md', 'README-metrics.md', 'index.md', '.git', '.github', '_utils', 'rst_include', 'venv', 'dev', '_data/**']
 
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = "sphinx"

docs/cql/cql-extensions.md

@@ -79,35 +79,6 @@ and to the TRUNCATE data definition query.
 
 In addition, the timeout parameter can be applied to SELECT queries as well.
 
-
-After [enabling object storage support](../operating-scylla/admin.rst#admin-keyspace-storage-options), configure your endpoints by
-following these [instructions](../operating-scylla/admin.rst#object-storage-configuration).
-
-
-Now you can configure your object storage when creating a keyspace:
-
-```cql
-CREATE KEYSPACE with STORAGE = { 'type': 'S3', 'endpoint': '$endpoint_name', 'bucket': '$bucket' } 
-```
-
-**Example**
-
-```cql
-CREATE KEYSPACE ks
-    WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy', 'replication_factor' : 3 }
-    AND STORAGE = { 'type' : 'S3', 'bucket' : '/tmp/b1', 'endpoint' : 'localhost' } ;
-```
-
-Storage options can be inspected by checking the new system schema table: `system_schema.scylla_keyspaces`:
-
-```cql
-    cassandra@cqlsh> select * from system_schema.scylla_keyspaces;
-    
-     keyspace_name | storage_options                                | storage_type
-    ---------------+------------------------------------------------+--------------
-               ksx | {'bucket': '/tmp/xx', 'endpoint': 'localhost'} |           S3
-```
-
 ## PRUNE MATERIALIZED VIEW statements
 
 A special statement is dedicated for pruning ghost rows from materialized views.
@@ -135,6 +106,15 @@ which is recommended in order to make the operation less heavyweight
 and allow for running multiple parallel pruning statements for non-overlapping
 token ranges.
 
+By default, the PRUNE MATERIALIZED VIEW statement is relatively slow, only
+performing one base read or write at a time. This can be changed with the
+USING CONCURRENCY clause. If the clause is used, the concurrency of reads
+and writes from the base table will be allowed to increase up to the specified
+value. For example, to run the PRUNE with 100 parallel reads/writes, you can use:
+```cql
+  PRUNE MATERIALIZED VIEW my_view WHERE v = 19 USING CONCURRENCY 100;
+```
+
 ## Synchronous materialized views
 
 Usually, when a table with materialized views is updated, the update to the

docs/cql/ddl.rst

@@ -312,14 +312,6 @@ Please use :ref:`Per-table tablet options <cql-per-table-tablet-options>` instea
 
 See :doc:`Data Distribution with Tablets </architecture/tablets>` for more information about tablets.
 
-Keyspace storage options :label-caution:`Experimental`
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-By default, SStables of a keyspace are stored locally.
-As an alternative, you can configure your keyspace to be stored
-on Amazon S3 or another S3-compatible object store.
-See :ref:`Keyspace storage options <admin-keyspace-storage-options>` for details.
-
 .. _consistency-option:
 
 Keyspace ``consistency`` options :label-caution:`Experimental`
@@ -637,7 +629,7 @@ Some examples of primary key definition are:
   key), and ``c`` is the clustering column.
 
 
-.. note:: A *null* value is not allowed as any partition-key or clustering-key column. A Null value is *not* the same as an empty string.
+.. note:: A *null* value is not allowed as any partition-key or clustering-key column. A *null* value is *not* the same as an empty string.
 
 .. _partition-key:
 

docs/cql/dml/insert.rst

@@ -67,9 +67,9 @@ Please refer to the :ref:`update parameters <update-parameters>` section for mor
 
 .. code-block:: none
 
-   movie    | director      | main_actor | year
+   movie    | director      | main_actor
-   ----------+---------------+------------+------
+   ----------+---------------+------------
-   Serenity | Joseph Whedon |    Unknown | null
+   Serenity | Joseph Whedon |    Unknown
 
 
 ``INSERT`` is not required to assign all columns, so if two
@@ -80,7 +80,7 @@ columns effects of both statements are preserved:
 
     INSERT INTO NerdMovies (movie, director, main_actor)
           VALUES ('Serenity', 'Joss Whedon', 'Nathan Fillion');
-    INSERT INTO NerdMovies (movie, director, main_actor, year)
+    INSERT INTO NerdMovies (movie, director, year)
           VALUES ('Serenity', 'Josseph Hill Whedon', 2005);
     SELECT * FROM NerdMovies WHERE movie = 'Serenity'
 

docs/dev/sstables-directory-structure.md

@@ -28,6 +28,7 @@ Scylla uses the following directory structure to store all its SSTables, for exa
     │   │   │       ├── ...
     │   │   │       └── mc-1-big-TOC.txt
     │   │   ├── staging
+    │   │   ├── quarantine
     │   │   └── upload
     │   └── cf-7ec943202fc611e9a130000000000000
     │       ├── snapshots
@@ -36,6 +37,7 @@ Scylla uses the following directory structure to store all its SSTables, for exa
     │       │       ├── ks-cf-ka-3-TOC.txt
     │       │       └── manifest.json
     │       ├── staging
+    │       ├── quarantine
     │       └── upload
     ├── system
     │   ├── schema_columnfamilies-45f5b36024bc3f83a3631034ea4fa697
@@ -167,6 +169,21 @@ The per-table directory may contain several sub-directories, as listed below:
   Used for ingesting external SSTables into Scylla on startup.
 
 
+* Quarantine directory (`quarantine`)
+  A sub-directory holding SSTables that have been quarantined, typically due to
+  validation failures or corruption detected during scrub operations.
+  
+  Quarantined SSTables are isolated to prevent them from being read or used by the
+  database. They can be inspected manually for debugging purposes or removed using
+  the `drop_quarantined_sstables` API operation.
+  
+  The scrub operation can be configured to handle quarantined SSTables using the
+  `quarantine_mode` parameter with the following options:
+  - `INCLUDE`: Process both regular and quarantined SSTables (default)
+  - `EXCLUDE`: Skip quarantined SSTables during scrub
+  - `ONLY`: Process only quarantined SSTables
+
+
 * Temporary SSTable directory (`<generation>.sstable`)  
   A directory created when writing new SSTables.
 

docs/dev/system_keyspace.md

@@ -375,6 +375,30 @@ Columns:
 * `tablets_allocated` - Number of tablet replicas on the node. Migrating tablets are accounted as if migration already finished.
 * `tablets_allocated_per_shard` - `tablets_allocated` divided by shard count on the node.
 
+## system.tablet_sizes
+
+Contains information about the current tablet disk sizes. Table can contain incomplete data, in which case `missing_replicas`
+will contain the host IDs of replicas for which the tablet size is not known.
+Can be queried on any node, but the data comes from the group0 leader.
+Reads wait for group0 leader to be elected and load balancer stats to become available.
+
+Schema:
+```cql
+CREATE TABLE system.tablet_sizes (
+    table_id uuid,
+    last_token bigint,
+    missing_replicas frozen<set<uuid>>,
+    replicas frozen<map<uuid, bigint>>,
+    PRIMARY KEY (table_id, last_token)
+);
+```
+
+Columns:
+* `table_id` - The table ID of the table for which tablet sizes are reported.
+* `last_token` - The last token owned by the tablet.
+* `missing_replicas` - Set of host IDs for replicas for which a tablet size was not found.
+* `replicas` - A map of replica host IDs and the disk size of the tablet replica, in bytes
+
 ## system.protocol_servers
 
 The list of all the client-facing data-plane protocol servers and listen addresses (if running).